D3.1 - Annex2 - Contributions of Partners.pdf - NIKER Project

NEW INTEGRATED KNOWLEDGE BASED APPROACHES TO THE PROTECTION OF CULTURAL HERITAGE FROM EARTHQUAKE-INDUCED RISK

NIKER Grant Agreement n° 244123

Deliverable 3.1 Inventory of earthquake-induced failure mechanisms related to construction types, structural elements, and materials ANNEX 2 – Contributions of Partners Due date: April 2010 Submission date: September 2010 Issued by: POLIMI

WORKPACKAGE 3: Damage based selection of technologies Leader: POLIMI PROJECT N°:

244123

ACRONYM:

NIKER

TITLE:

New integrated knowledge based approaches to the protection of cultural heritage from earthquake-induced risk

COORDINATOR: Università di Padova (Italy) START DATE:

01 January 2010

INSTRUMENT:

Collaborative Project Small or medium scale focused research project

THEME:

Environment (including Climate Change)

Dissemination level: PU

DURATION: 36 months

Rev: FIN


1


PARTNER N° 2 AND 17 - BAM AND ZRS ............................................................... 1 1.1

Damage observed in adobe buildings .......................................................................... 1

1.2

Earth building ............................................................................................................. 22

1.2.1 Earth building: masonry typology ............................................................................ 22 1.2.2 Earth building: building typology ............................................................................. 27 1.2.3 Conclusions ............................................................................................................ 37 1.2.4 References ............................................................................................................. 38

2

PARTNER N° 4 - NTUA.......................................................................................... 43 2.1

Construction types of masonry, walls connection, floors, roofs and vaults .................. 43

2.1.1 Construction types of masonry................................................................................ 43 2.1.2 Walls connection..................................................................................................... 53 2.1.3 Floors and roofs ...................................................................................................... 57 2.1.4 Vaults ..................................................................................................................... 62 2.2

Churches typologies ................................................................................................... 64

2.3

Damage examples ..................................................................................................... 70

2.4

Timber reinforced structures in greece: 2.500 b.c-1.900 a.d. ...................................... 77

2.5

Effect of timber ties on the behaviour of historic masonry ........................................... 85

2.6

Timber reinforced masonry systems in Greece .......................................................... 97

2.7

Intervention with use of RC tie beam ........................................................................ 109

2.8

DAMAGE ABACUS : ................................................................................................ 112

2.8.1 Timber reinforced masonry - Decay of wood......................................................... 112 2.8.2 Timber reinforced systems - Construction errors................................................... 113

3

4

PARTNER N° 8 – UBATH .................................................................................... 116 3.1

Collapse Mechanisms and Crack Patterns of Herringbone Pattern Masonry Vaults . 116

3.2

FRP reinforced masonry arches ............................................................................... 141

3.3

Facades mechanisms .............................................................................................. 166

3.4

mechanisms for abacus ........................................................................................... 168

PARTNER N° 10 - ENA ........................................................................................ 169 4.1

Local construction practices and damage mechanisms ............................................ 169

4.1.1 Introduction ........................................................................................................... 169 4.1.2 The historic buildings face to earthquakes ............................................................ 177 4.1.3 Local construction practices .................................................................................. 183 4.1.4 Historical buildings protection strategy .................................................................. 187 Damage based selection of techniques

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4.1.5 Dwellings stock seismic vulnerability assessment in urban areas ......................... 189 4.1.6 Componennet typologies and damage mechanisms ............................................. 199 4.1.7 Building typologies and damage mechanisms ...................................................... 201

5

PARTNER N° 11 - CDCU ..................................................................................... 206 5.1

Architecture and constructions in Egypt: building materials and techniques ............. 206

5.1.1 Introduction ........................................................................................................... 206 5.1.2 Building Materials and Techniques ....................................................................... 206 5.1.3 Construction Techniques in Egypt ........................................................................ 217

6

PARTNER N° 18 - MONU..................................................................................... 274 6.1 Using advanced composites to retrofit Lisbon’s old “seismic resistant” timber framed buildings ............................................................................................................................. 274 6.2 Rehabilitation of Lisbon’s old “seismicresistant” timber framed buildings using innovate techniques .......................................................................................................................... 290 6.3 Cap- VI - Comcepção e projecto das intervenções de reabilitação estrutural” and “Cap. X – Análise estrutural e verificação de segurança” in «Reabilitaçao Estructural de Edificios Antiguos»,GeCoRPA ............................................................................................ 303 6.4 “Sismo 1998 - Açores - uma década depois” - Ediçao C. Sausa Oliveira, Aníbal Costa, João C. Nunes, 2008 .......................................................................................................... 337

7

PARTNER N° 7 – UPC ......................................................................................... 367 7.1 Structural features and collapse mechanisms of houses and churches. Typical urban buildings and gothic churches in Barcelona ........................................................................ 367

8

PARTNER N° 12 – IAA ........................................................................................ 401 8.1

7 typologies of the buildings of the APP ................................................................... 401

Damage based selection of techniques

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1 PARTNER N° 2 AND 17 - BAM AND ZRS 1.1

DAMAGE OBSERVED IN ADOBE BUILDINGS

DAMAGE OBSERVED IN ADOBE BUILDINGS, TYPOLOGY Damage based selection of techniques

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1.


OVERTURNING OF FAÇADE, GABLE OR NON-LOADBEARING WALL DUE TO OUT-OFPLANE FORCES

Building

Damage

Main Estate House, Hacienda San José, Cañete, Pisco, Peru

Damage description

Source, Photo Copyright

Out-of-plane collapse of nonloadbearing wall due to lack of proper wall-roof connection

Cancino 2009

Out-of-plane collapse of Gable-End wall due to lack of proper wall-roof connection

Tolles et al. 1996

2007 Pisco Earthquake

De la Osa Adobe, California

1994 Northridge Earthquake

DAMAGE OBSERVED IN ADOBE BUILDINGS, TYPOLOGY


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2.


OUT-OF-PLANE MECHANISM OF FAÇADE, GABLE OR NON-LOADBEARING WALL

Building

Damage

Damage description Out-of-plane mechanism of gable-end wall

Church in San Pedro in Coayllo, Peru

Source, Photo Copyright ICOMOS 2006/2007 © Rommel Angeles Falcon




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3.


IN-PLANE MECHANISM OF FAÇADE, GABLE OR NON-LOADBEARING WALL

Building

Damage

Damage description On left hand side, pre-existing crack

Andres Pico Adobe, California

On right hand side, in-plane shear cracking and failure

Source, Photo Copyright Tolles et al. 2002

1994 Northridge Earthquake

School, Esfikan Village, Iran

In-plane cracking

Halcrow 2003

In-plane cracking of façade, possibly façade was reinforced. This is not specified in the publication

EEFIT 2007

2003 Bam Earthquake

Church in the vicinity of Guadelupe, Peru



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DAMAGE OBSERVED IN ADOBE BUILDINGS, TYPOLOGY 4.

CRACKING OF ARCH OPENINGS

Building

Damage

Lo Vicuna Hacienda, Chapel, Putaendo, Chile

Damage description


Cracking of Arch opening

© Urs Müller 2010


© Urs Müller 2010


Satprem MaÏni 2004

1985, 1987, 1995 Chile


1985, 1987, 1995 Chile

Arg-EBam, Iran

2003 Bam


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CRACKING OF BARREL VAULTS

Building

Damage

School, Esfikan Village, Iran

Damage description


Longitudinal cracking of Barrel Vault

© Halcrow 2003

Transverse cracking of Barrel Vault

EERI 2004 © Bijan Khazai

Longitudinal cracking of Barrel Vault

Satprem MaÏni 2004

2003 Bam

Arg-eBam, Iran

2003 Bam

Arg-E-Bam, Iran

2003 Bam


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IN-PLANE CRACKING OF LOADBEARING WALLS

Building

Damage

Leonis Adobe, California

Damage description


In-plane shear cracking of loadbearing wall

© Tolles 1996

In-plane shear cracking of loadbearing wall

EEFIT 1982

Collapse, supposedly due to in-plane shear

EEFIT 1982

1994 Northridge

Yalnitzba g, Turkey

1982 Erzinkan

Yalnitzba g, Turkey

1982 Erzinkan


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OUT-OF-PLANE CRACKING OF LOADBEARING WALLS

Building

Damage description

Damage

Leonis Adobe, California


Out-of-plane cracking of loadbearing wall

© Tolles 1996

Out-of-plane cracking of loadbearing wall

© Tolles 1996

1994 Northridge

Andres Pico Adobe, California

1994 Northridge



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8.


. WALL CRACKING OR DISCONTINUITY

Building

Damage

Convento at the San Gabriel Mission, California

Damage description


Separation between two interior walls

© Tolles 1996

Vertical cracking at perpendicular walls, external

ZRS 2010

1994 Northridge

Bin Suroor – Eastern house – Mutaredh Oasis

2002 Masafi



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9.


DETACHING OF WALL FROM HORIZONTAL ELEMENTS

Building

Damage

Pio Pico Adobe, California

Damage description


Crack between wall and roof

© Tolles 1996

Crack between wall and roof

© Tolles 1996

Damage at interface between ceiling joists and wall

© Tolles 1996

1994 Northridge

Pio Pico Adobe, California

1994 Northridge

Del Valle Adobe, California

1994 Northridge


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CORNER CRACKING, DAMAGE OR COLLAPSE

Building

Damage

Pio Pico Mansion, California

Damage description


Vertical cracking at corner

© Tolles 2002

Separation at Corner

© Urs Müller 2010

Collapse of corner

© Rancho Camulos Museum 1994, from Crosby (year unknown)

1994 Northridge


1985,1987,1997 Chile

Rancho Camulos, California

1994 Northridge


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CRACKING OR COLLAPSE OF TOWERS

Building

Damage

Damaged Jame Mosque, Borujerd City, Iran

Damage description


Vertical cracking at perpendicular walls, external

© Tolles 2002

Partial collapse of one tower, presence of materials other than adobe, also for restoration purposes, is likely

EEFIT 2007, Cancino 2009

2006 Borujerd, Iran Iglesia del Carmen, Chincha, Pisco area, Peru

1982 Erzinkan



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12.


OUT-OF-PLANE CRACKING OR BREAKING AT MID-

L

Building

Damage

Mission San Fernando, California

Damage description


Out of plane collapse

© Tolles 2002

1994 Northridge DAMAGE OBSERVED IN ADOBE BUILDINGS, TYPOLOGY


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1.


VERTICAL CRACKING , SOME CRACKING STARTS AT BASE AND STOPS AT LIFTS, SOME RUNS THROUGH THE HEIGHT OF THE WALL


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Building

Damage


Damage description

Lo Vicuna Hacienda , Putaendo , Chile


Vertical cracking starting at base of wall and stopping at first horizontal course from bottom

Urs Müller

Vertical Cracking

Josefine Krause 2009

1985, 1987, 1995 Chile Earthquakes

Ladakh, India

Earthquake unknown, Area is Earthquake-Prone


2.

VERTICAL CRACKING AT CORNERS


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Building

Damage


Damage description


The gTsug-lagkhang of Kanji, Western Himalaya

Vertical Cracking at corner

The University of Graz, http://bks.tugraz.ac.at/~n euwirth/neuw eb/fwf_fsp_ne tz/kanji_25.ht m

Nangmal Tsempo, Leh, Ladakh, India

Vertical Cracking at corner (also note cracking round openings)

© Paul Jaquin 2008 http://www.his toricrammede arth.co.uk/indi a.htm



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3.


IN-PLANE SHEAR CRACKING

Building

Damage

Ladakh

Damage description


Diagonal Cracking

Hurd 2006

Diagonal Cracking

© Paul Jaquin 2008 http://www .historicra mmedeart h.co.uk/in dia.htm

Ladakh 2005 (unknown if picture was taken previously) Shey, Ladakh, Tibet

Ladakh 2005


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1. VERTICAL CRACKING; SOME STARTING AT BASE AND STOPPING AT LIFTS; SOME EXTENDING TO TOP OF WALL; WHICH CAN RESULT IN OVERTURNING OF SINGLE INDEPENDENT SECTIONS

Building

Damage

Damage description Vertical Cracking and possibly termite infestation

Arg-e-Bam


EERI Bijan Khazai 2004

2003 Bam



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2. VERTICAL CRACKING AT CORNERS

Building

Damage

Dwelling, Bam

Damage description


Cracking at corner

Halcrow 2003

2003 Bam



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REFERENCES Cancino, C.N. (2009) “Damage Assessment of Historic Earthen Buildings after the August 15, 2007 Pisco Earthquake, Peru” In collaboration with: Stephen Farneth, Philippe Garnier, Julio Vargas Neumann, Frederick Webster and Dina D’Ayala, The Getty Conservation Institute, Los Angeles, 2009. Crosby, A. “Base Recording: Gathering Information” http://getty.museum/conservation/publications/pdf_publications/illustrated_examples2.pdf, last accessed April 2010 EEFIT (1982) “The Erzincan, Turkey Earthquake of 13 March 1992 – A field report by EEFIT”, Earthquake Engineering Field Investigation Team, The Institution of Structural Engineers, London EERI (2004) “Preliminary observations on the Bam, Iran, Earthquake of December 26, 2003”, Learning From Earthquakes, Earthquake Engineering Research Institute, Special Report, April 2004. EEFIT (2007) “August 15 Magnitude 7.9 Earthquake near the Coast of Central Peru” A field report by EEFIT”, Earthquake Engineering Field Investigation Team, The Institution of Structural Engineers, London Halcrow (2003) “The Bam, Iran Earthquake of 26 December 2003”, Field Investigation Report Prepared By: Dr. Ali Reza Manafpour, Halcrow Group Limited Hurd, J. (2006) “Observing and Applying Ancient Repair Techniques to Pise´ and Adobe in Seismic Regions of Central Asia and Trans-Himalaya”, Proceedings of the Getty Seismic Adobe Project Colloquium, The Getty Conservation Institute, pp. 101-108. ICOMOS (2008) “Heritage at Risk, H@R 2006/2007”, International Council on Monuments and Sites, Published by E. Reinhold-Verlag, Altenburg, 2008. MaÏni 2004 Post Earthquake Assessment of Vaulted Structures at Bam, Iran http://www.earthauroville.com/index.php?nav=menu&pg=projects&id1=3&txt=text, last accessed April 2010 Tolles, E. L., Kimbro, E. and Ginell, W.S. (2002). “Planning and Engineering Guidelines for the Seismic Retrofitting of Historic Adobe Structures”. Los Angeles: The Getty Conservation Institute, 2002. Tolles, E. L. (2006) “Getty Seismic Adobe Project Research and Testing Programme”, Proceedings of the Getty Seismic Adobe Project Colloquium, The Getty Conservation Institute, 2006, pp. 34-41.


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1.2


EARTH BUILDING

1.2.1 Earth building: masonry typology 1.2.1.1 introduction Load-bearing earth construction (illustrated in Figure 1) can be subdivided into: - Adobe, or (unfired) Earth Blocks - Rammed Earth, Taipa or Pisé - Cob

Figure 1 Different earth building techniques: adobe, rammed earth, cob (from left to right)

These materials differ in mechanical, physical and chemical properties. While in general terms it can be said that the seismic behaviour of earthen structures is characterised by brittle behaviour, parametric studies comparing structural behaviour according to building technique (whether static or dynamic) are few in the literature. One exception is Vargas Neumann et al. (1993), in which the seismic behaviour of rammed earth and adobe are compared. The understanding and modelling of structural behaviour of earth structures is limited by a lack of consistent testing of the mechanical properties of their constituent materials. Adobe / Unfired Earth Block Masonry units in historic adobe structures are inconsistent in shape and size, as shown in Figure 2. Figure 1. Varying sizes of adobe units throughout the world sorted by country of origin (non exhaustive)

Figure 2 Varying sizes of adobe units throughout the world sorted by country of origin (non exhaustive)

Mortar used in adobe construction is usually based on an earth binder (sometimes combined with lime, CORPUS 2010a), whereas sand, gravel and chopped straw are used as aggregates. Joint thickness (tj) varies from tight, 0,1 tm (tm is masonry unit thickness to broad 0,5 tm < tj = 1 tm. Wall thickness varies between 30 – 150 cm. Typical adobe wall typologies are shown in Figure 3. In many historical adobe buildings, wall slenderness is (height-to-thickness) is < 5. Walls are in some cases tapering. Figure 3 Adobe wall typologies One-leaf (single wythe)

Two-leaf (double wythe), connected


Two-leaf (double wythe), poorly connected or not connected

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Adobe structures the only earthen structures listed in the 1998 European Macroseismic Scale (Grunthal 1998), according to which, together with rubblestone, they are the most vulnerable to earthquakes. Data gathered after the destruction caused by the 1994 Northridge Earthquake indicates that a peak ground acceleration (pga) of 0.1-0.2 g is sufficient to initiate damage in well-maintained unreinforced adobe masonry buildings (Webster 2006). Adobe seems to fail from cracks in the mortar, with cracks usually following stepped patterns along the mortar joints (Vargas Neumann et al., 2006). This behaviour can also observed in Hardwick and Little (2010)´s testing model: though some bricks had cracked in half rather than along the mortar lines, most cracks follow the mortar patterns. At a global level, the failure of adobe is so described by Vargas Neumann et al. 2006: 1. Significant cracking starts in regions subjected to tension, it starts at the lateral corners of the walls as well as at corners of doors and windows 2. Out of plane rocking causes large vertical cracking that separate walls from one another 3. Walls overturn 4. Walls break into separate pieces, which may collapse independently Typical seismic-includes damage to adobe buildings (Tolles at al. 1996) is not limited typical damage observed in other masonry (in-plane X-cracking, out-of-plane gable wall failure, out-of-plane collapse of wall subjected to high confining forces). It also includes, assumingly at lower stress than for fired brick masonry, the damage typologies shown in Table 1. Table 1 Typical earthquake-damage in adobe buildings

Out-of-plane flexure in loadbearing walls This type of damage to earthen buildings was reported, in the case of loadbearing walls, to mainly result in cracking, leaving walls stable.

Slippage between walls and wood framing Roof, ceiling, and floor framing often slips at the interface with the adobe walls due to inadequate connection to the adobe walls. Horizontal upper-wall cracks: horizontal cracks may develop near the tops of walls when there is a bond beam or the roof is anchored to the beam.


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Moisture damage contributions to instability Out-of-plane instability (or a contribution to instability) is caused by weakening or erosion, usually at the base, or saturation or repeated wet/dry cycles resulting in weakened slip-planes at the base of the wall along which the wall can slip and collapse. Corner damage Damage often occurs at the comers of buildings due to the stress concentrations that occur at the intersection of perpendicular walls. Instability of comer sections often occurs because two sides of the comer are unrestrained. Therefore, the comer section is free to collapse outward from the building. Vault/Dome damage From photographic documentation, seems attributable to failure of side walls

An attempt to define a collapse mechanism was proposed by Kiyono and Kalantari (2004), who attributed the catastrophic collapse of Bam (Iran) to “improper” bonding strength of mortar. It should be noted that the results of the bonding strength tests (tension and shear) show considerable variation, and that no more than 12 samples were tested. Collapse mechanisms proposed are three: 1) Overturning of wall (monolithic) – as per Section entitled “Simple Overturning” 2) Slippage 3) Failure of bond between bricks, when stability is provided by weight of roof or bricks.

Rammed Earth Historic rammed earth walls are formed by ramming layers of earthen material within formwork. Each layer of rammed earth is known as a lift, and at many historic rammed earth sites material such as lime, straw, stones and bricks is placed between the lifts (Jaquin 2006). Sizes reported (CORPUS 2010a) for each module (what is rammed within one formwork box) are 1-3 metres in length and 30-50cm in height, but the author has observed layer heights up to 1m. According to whether the formwork is fastened externally or internally, holes are present. (Jaquin 2006). Different typologies of rammed earth walls are shown in Figure 4 Different typologies of rammed earth walls, after Jaquin (2006) .

Figure 4 Different typologies of rammed earth walls, after Jaquin (2006)


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Based on the literature1, rammed earth is categorised as follows: 1. Lime / earth outer face with sand/gravel core 2. Lime / earth (tapial real), homogeneous 3. Earth with low lime content No mortar is used between units. However, in some cases, lime, straw, stones, turf, vegetable matter or bricks are rammed between layers. Langenbach (2004) and Hurd (2006) suggest that these ‘mattresses’ between layers are a seismic protection measure since they act as weak layers which force diagonal shear cracks to propagate horizontally thus preventing collapse. Even when no layers are placed between lifts, the fact that the construction process progresses horizontally before progressing vertically means that the bond between lifts are weaker than those compacted within the formwork, and are usually visible (Jaquin 2006).The thickness of rammed earth walls is determined by the formwork in which it is rammed. Walls are therefore one-leaf. Joints are,, “staggered”, as in brick masonry.

Figure 5 Typical earthquake-damage in rammed earth buildings

Vargas Neumann et al. (1993) described research carried out to assess the performance of rammed earth walls under seismic loading, with the aim of identifying parameters which influence seismic vulnerability. Parameters chosen and tested were: Soil granulometry, Humidity content, Compactation level, Use of natural additives, and “joint treatment”, i.e. presence of materials between layers. The results of the study, which was conducted in order to allow comparison of rammed earth walls with adobe walls, showed a higher resistance and deformation of rammed earth walls in comparison with adobe walls (up to 40%). Current anti-Seismic buildings codes for earth buildings (NZS 1997) do not take this difference in consideration. Cob Cob is a mixture of clay subsoil, aggregate and straw. Walls are built without shuttering on a stone plinth. Literature on the subject of cob in seismic areas is known by the author to be limited to Langenbach (2004). Fodde (2008, 2009) documents the presence of cob and its repair methods (as well as adobe and rammed earth) in Central Asia, in relation to seismic and other structural damage. Extensive testing on the compressive strength, density and Young´s Modulus in relation to moisture content was carried out by Ziegert (2002).

1

Graciani García and Tabales Rodríguez (2003), Gallego Roca and Valverde Espinosa (1993), and Jaquin (2007)


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Figure 6 Typical earthquake-damage in cob buildings

1.2.1.2 Roofs / Earthen buildings Roof typologies reported for historical earthen structures are illustrated in Table 2. With the exception of domes and vaults constructed out of adobe, roofs are constructed in timber or wattle and daub (quincha in Spanish), and then sometimes covered in earth and plaster. Table 2 Roof typologies reported for historical adobe structures

Wooden Flat Roof, no bond beam, heavy

Timber Flat Roof, with timber bond beam

Iran, Afghanistan

Turkey Adobe

Adobe Dome/Vault

Timber Pitched Roof trusting on wall

Iran (generally Middle East)

South America

1.2.1.3 Foundations Vertical loads are usually transmitted to the ground by means of stone or rubble foundations. These may allow moisture to permeate and therefore weaken the walls (Navarro Grau et al. 2006).

1.2.1.4 Openings Traditionally, openings in earthen structures are of limited size and constructed by means of wooden lintels. Typical sizes reported by CORPUS (2010) for adobes in the Mediterranean area are 15x 20cm, 30-40 x 75-125 cm for window openings and 100-130cm x 210-300cm.


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Typical sizes reported by CORPUS (2010b) for rammed earth are approximately 40 cm x 40 cm for window openings and 100 cm x 300 cm for door openings. In Arab countries, building typologies include the presence of niches.

1.2.2 Earth building: building typology Isolated buildings are quite frequent in earth construction. Typical floor plans are shown in Figure 7. Single as well as multiple storey buildings are found. Originally, earthen buildings are characterised by simplicity in plan and elevation. With the exception of colonial buildings in California and South America, possibly inspired by fired brick architecture in Europe, buildings are found to be round and square in plan. Figure 7 Some plans of isolated earth buildings

L ≈ 50-60m

Fujian Tulou Collective Housing China Rammed Earth

Temples and Rapaz Missionary dwellings Religious Building India Peru Rammed Adobe Earth and Adobe

Las Flores Adobe Ranch House California Adobe

1.2.2.1 Multi-Storey Buildings Adobe brick walls, loadbearing, topped by timber beams at storey/roof levels Adobe houses with timber bond or ring beams belong to the vernacular architecture of different countries. Those of Kashmir and Nepal are interesting examples of vernacular architecture showing signs of seismic-resistant features. Taq houses (Kashmir) consist of adobe walls held together by horizontal timber bond beams, or runners, which are continuous around the perimeter of the building, and present at each floor and roof level. The floor beams and the wall beams lap over each other, so tha. the walls are tied together with the floors. Gosain and Arya (1967) suggest that the weight of the masonry "prestresses" the wall, contributing to its resistance to lateral forces. Some of the characteristics of these buildings oppose some of today's commonly-accepted practices: mortar of negligible strength was used; masonry leaves are poorly bonded; roofs are heavy. However, both Neve (1885) and Gosain and Arya (1967) reported relatively undamaged survival of buildings 3-5 stories after earthquake damage. The literature suggests that this is due to the damping resulting from the friction induced in the masonry of Taq walls, estimated to be in the order of twenty percent, compared to four percent in uncracked modern masonry (brick with Portland cement mortar) and six to seven percent after the masonry has cracked (Gosain and Aryia 1967). The timber runner beams and floor diaphragms keep the individual piers from separating, which would cause the house to break apart, so that even though the mortar is extremely weak,


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causing the wall to yield under a much smaller load, the masonry continues to have a good chance of holding together. DÁyala (2006) has thoroughly studied a similar housing typology, the newari, in the Kathmandu Valley, Nepal (DÁyala and Bajracharya 2003). Traditional newari houses are usually independent, rectangular, three-storey houses, in plan about 6m by 4-8metres. A vernacular anti-seismic measure reported by DÁyala is the presence of chokus, wooden pegs which restrain the sliding of floor joists over adobe walls, the presence of which prevents the facade from failing under overturnig and, instead, cause it to fail due to an arch effect mechanism (see Figure 8). Beams ran originally over both masonry leaves, but are recently only being constructed over the internal leaf. These beams seem in the literature (Langenbach 2000 and DÁyala 2006) to be constructed above the walls only, and that walls are thus not connected at corners. The seismic vulnerability of this construction type, proven by their high rate of survival in earthquakes to be relatively low, is reported by DÁyala to be increased by the introduction, at a later date, of party walls that are not necessarily connected to the facade and might run through the middle of a row of openings. New staircases are sometimes also introduced, and windows widened to such an extent that entire facade walls are missing at certain stories. In general terms, the differences in building material and mass which result from changes made in newari houses over time have significant consequences on the seismic vulnerability of the original unit.

Figure 8 Facade mechanisms of failure, DÁyala 2006

The most common cause of seismic vulnerability increase in houses in the Kathmandu valley was reported by DÁyala (2006) to be the use of the dalan, a timber frame used in conjunction with adobe building, consisting of columns pinned to the ground below and pinned to the beams above. The use of pinned connections means that the use of the dalan can be compared to that of a soft-storey structure, and its failure mechanism as that of a soft-storey as well (see Figure 9).


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Figure 9 Soft-storey failure mechanism in newari house with dalan wooden structure

Rammed earth multi-storey buildings The Tulou (see Figure 10) is a unique building typology found in South-East China. The massive rammed earth peripheral walls are up to 4-storeys in height and enclose storehouses, wells and bedrooms for hundreds of dwellers More than twenty thousand tulou are still standing and some are still inhabited. Tulou are usually rectangular or round in plan. One of the largest is Zaitianlou in Zhaoan, with 2,4 m thick walls and a diameter of 91 meters. Tulou “houses” have been said to be “earthquake-resistant” buildings (Minke 2006).

Figure 10 Tulou housing, different typologies (after Huang Hanmin 1991)

Unlike some other historic structural materials, earth buildings, are highly susceptible to Cracking, Rising Damp and Salt Damage, Erosion, Termite Infestation, and generally loss of section cause irregularities in strength, stiffness and mass which majorly contribute to poor performance under earthquake conditions. Structures affected by these conditions will clearly be affected at lower pga than the 0.1-0.2g reported by Webster (2006) to start damage in adobe buildings. Taking Bam, Iran, as an example, the collapse mechanisms theories proposed by Kayano and Kalantari do not suffice in explaining why some of the dwellings were still standing after the earthquake (Langenbach 2004, JSEE 2004). Langenbach´s explanation is that the conditions of the buildings at the time of the earthquake was very poor. While JSEE (2004), who noticed the good performance of the arch roof of the old adobe buildings, attributes the failure of other buildings to improper and lack of seismic safety consideration in the restoration program and the presence of heavy roofs and walls, as well as the lack of structural integrity especially in newly built buildings, Langenbach (2004) attributes the catastrophic collapse of the Arg-e Bam to internal wall degradation. Damage based selection of techniques

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Cracking Cracking in earthen buildings is common as from the moment they are built, and is set off by shrinkage straight after construction. Shrinkage cracking is then worsened by conditions such as weathering and differential settlement. Rising Damp, Salt Damage and Erosion The influence of moisture and salt content on the compressive strength of earthen materials has been extensively researched by Ziegert (2003). A detailed analysis of the erosion process in relation to rising damp and salt damage, can be found in Fujii et al. (2009). Termite Infestation Langenbach (2004) attributes the catastrophic collapse of the Arg-e Bam due to internal loss of cohesion and to termite infestation.

1.2.2.2 Failure of earth materials At a local level, failure of earthen materials may be viewed in three steps (Chaudhry, 2007): 1) Crack initiation – already present after construction or weathering 2) Crack propagation – cracking runs parallel in the direction of tensile stresses, it grow as a result of continuously applied stresses 3) Failure – when the material that has not cracked cannot withstand the stress. This stage happens early in the case of brittle materials like earth. In the case of rammed earth and cob, the horizontal layers between lifts observed by Hurd (2006) Turkey, Armenia and Iran, are claimed to limit crack propagation and prevent collapse and to act as ring beams. The same principle, carried out by introducing geogrid horizontally throughout the walls at regular intervals, is currently being applied in the New Zealand Earth Building Code (NZS 1997). Earth construction Traditional means of repairing earthquake damage to earth construction Crack repair Technique Nature of technique Material Location/Source 1. Demolish adobe Traditional, currently used Adobe Navarro Grau et al. 2006 and rebuild 2. “Soft stiching” Traditional, currently used but Cob and Hurd 2006 only reported Rammed earth 1. Demolish and rebuild Navarro Grau et al. (2006) describes the repair of a severely cracked corner by means of demolition and new build, and justifies it by explaining that the current state of the art of injection techniques do not guarantee structural integration of walls, which is necessary to reinstate a monolithic behaviour. Navarro Grau et al.(2006) also claim that the use of grout Damage based selection of techniques

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injections resulting in rigid material, such as cement mortars, is not recommended in earth construction because it creates stiffness discontinuities in the masonry which would result in stress concentration and thus new cracking in case of seismic loading. 2. “Soft stiching” “Soft stitching” is a repair procedure carried out by Hurd (2006) which makes use of various materials such as flat adobe “bats”, thick tiles, hemp, fibre mats or stainless steel expanded metal lath introduced into a groove cut across the crack needing repair. The groove is cut to about half the wall thickness wall, over the crack, with deep returning ends in the form of a staple and continually wetted down with water during the construction process to eliminate suction. The chase is then filled with alternate layers of fibres and adobe blocks until the top course, which is 10-15 cm deep, is reached. This is then wetted down and dry packed with loose material identical to that of the adobe blocks. So as to form a dense rammed fill. This procedure is carried out internally and externally. Hurd (2006) recommends the use of stitches of varying length “to allow for stitching of subsidiary cracks and to prevent the formation of the new cleavage planes that may develop from stitches of regular length”. Soft stitching is not known by the author nor by Hurd (2006) to test or examine the engineering performance of soft stitching under dynamic loading. Hurd (2006), however, claims to have observed “the use of still-functional stitches”, i.e. after an earthquake of unknown magnitude.

Figure 11 “Soft” stitching carried out by Hurd in 2004. (Photo: Jaquin 2008)

Means to reduce earthquake damage Vernacular means Additional elements 1. Bond beam To prevent: Lack of connection between perpendicular walls Damage based selection of techniques

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2. 3. 4. 5.


External horizontal wall ties, Nepal (Chaudhry and Sikka 2006) Vertical wall ties, Nepal (Chaudhry and Sikka 2006) Buttresses (ZRS Photographic Database, Oman) Males, or horizontal “mattresses” or layers in rammed earth or cob

Design considerations 1. Thickness It has been claimed in the literature that in historical buildings, where height/thickness ratio is often < 5 (Tolles et al. 2002), wall thickness is often sufficient to prevent overturning as the walls are difficult to destabilize even when they are severely cracked. 2. Roof Support provided at the top walls by a roof system may add additional stability to the walls. This point is contended by researchers. While a flexible and rigid roof is often claimed to be an appropriate solution, the presence of additional loading on the walls might provide additional stability (Webster 1995). 3. Openings Retrofitting 1. “Hard”, i.e. Modern stainless steel stitching 2. Grout injection Modern

Cob and Hurd 2006, Rammed Schröder 2010 earth Adobe Chaudhry 2007

1. Grout injection The use of low pressure grout injection is described by Webster (2006). Strength design Strength-based retrofit is based on introducing and independent structural frame of reinforced concrete or steel, requiring the removal of large amounts of historic material (Hardy, Cancino and Ostergren). The use of reinforced concrete is a practice which in the past has and is sometimes still applied to earthen constructions, according to the same engineering strength-design principles which lead do the use of reinforced concrete for the restoration of other masonry structures. For instance, prior to the publication of the CHBC California Historical Building Code (CHBC), made mandatory in 1985, seismic retrofitting for adobe buildings in California was based on the UBC, which does not recognise any seismic load resistance for adobe. Therefore, retrofitting consisted in adding shear walls and constructing independent steel or concrete structures designed to carry all loads from horizontal members. This resulted in the destruction of historic fabric and removal of stabilising loads at the tops of adobe walls.


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The validity of applying strength design concepts to earthen structures has not been proven in practice to be effective. On site observation of seismic damage to earthen structures (Langenbach 2004; Cancino 2009; Navarro Grau et al. 2006) indicate, on the contrary, that the presence of reinforced concrete elements has lead to the damage, and not the protection, of earthen structures. Strength design is also at the basis of the use of steel reinforcement bars as a means of reinforcing earthen walls. Since earthen walls do not bond with conventional rebar and therefore, the yielding stress conditions on which strength design is based cannot be met, the use of steel as internal reinforcement has also been opposed (Webster 1995). Reinforcement (steel) can bond to the adobe if embedded in cement mortar or grout (Chaudhry 2007) but might results in stress concentration and thus new cracking in case of seismic loading.. It is claimed (Barrow et al. 2006) that thick adobe walls do have energy dissipation characteristics in the post-elastic phase. As well described by Langenbach (2004), if both the restored houses in Arg-e-Bam and the new houses suffered more than the untouched ancient abandoned earthen ruins in the desert nearby, as also reported by JSEE (2004), then “the problem had less to do with earthen construction per-se than it had to do with the particular form of earthen construction that was practiced in modern Bam”. Stability design Stability-based retrofitting (Webster 2006), which has been introduced more recently, is less invasive, and consists in limiting relative displacement between elements of a structure and using gravity as a restoring force”. Since the overturning of walls is the first mode of failure common to adobe buildings (Tolles 2006), the first step towards stability under earthquake loading is to attach a structure´s vertical elements to its horizontal elements . For instance, for gable walls or any walls susceptible to overturning (i.e. of thinner walls between support points), full-height centre core rods can be introduced to provide restraint, prevent outof-plane failure, and increase wall ductility in both in-plane and out-of-plane directions (Tolles 2006) Stability-based measures do not stiffen the structure and do not come into play until old cracks reopen, new cracks have developed, and enough displacement occurs to engage the stabilising measures, which work in two ways (Webster 2006): 1) They increase structural damping due to friction hysteresis across the cracks 2) They lower response frequency caused by the rocking of walls Webster (2006) provides examples of historical buildings in California where stability-based measures were used between 1992 and 2005. Stability based methods, after Webster (2006), with some additions, are considered at three different levels: 1) Structural continuity at floor/roof 2) Out-of-plane overturning stability 3) Containment of wall material Damage based selection of techniques

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1) Structural continuity at floor/roof level

Examples

2) Out-of-plane overturning stability - Anchoring together roof, walls, and floors, c) Design of the fibre-rods based on 0.8* weight of the gable-wall section above bond beam (Webster 2006). Advantages of earthen grouts (Barrow et al. 2006) are compatibility with historic adobe and reversibility (Barrow 2006): the consist of adobe soil, sand, a small amount of Portland cement, ground additive (Sika ground aid) to minimise shrinking during curing. Examples

3) Containment of wall material



a) Existing (or introducing a) timber bond beam interconnecting all walls b) Top-of-wall continuity (stainless steel straps, cables), through-wall tied c) Connecting discontinuous existing bond beam elements, incl. previously reinforced beams introduced d) Addition to a): introduction of wooden pegs as shear connectors Aim: lateral restriction, preventing rocking or overturning of walls a) Navarro Grau et al. 2006 a) Sikka and Chaudhy 2006. Nako preservation project b) Hurd 2006 c) Webster 2006, Shafter Courthouse, USA

a) Top-of-wall pins (steel or fibreglass) (grouted in place with a fly-ash/soil mixture (Roselund 1990) b) Whereas Tolles 2006 mentions epoxy grout being used with stainless steel tie rods c) Vertical center core rods (steel or fibreglass) d) Diaphragm (partial or full, i.e. plywood) e) Top-of-wall anchorage f) Through-wall floor anchorage (in the case of Tolle 2006, with viscous dampers)

Aim: lateral restriction, preventing rocking or overturning of walls d) Tolles 2006, testing model

a) Horizontal and/or vertical straps or cables, through-wall tied b) Horizontal and/or vertical center core rods c) Surface mesh, through-wall tied (polymer

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with mud plaster or welded wire mesh) d) Top-of-wall continuity hardware, throughwall tied, in conjunction with top of wall pins Examples

c) Torrealva et al. (2006) tested Polymer mesh geogrid completely covering the walls on both sides. The mesh was connected with plastic threads through a whole previously drilled in the wall. Spacing every 40cm (Torrealva et al, 2006). Covering the wall with mud plaster greatly increases the initial shear strength and stiffness of wall, controlling the lateral displacements and precenting the cracking of the wall to great extent. The cost of the mesh technique can be reduced by placing mesh only at.. not over the whole wall. The amount of mesh is more important than the quality of the mesh Torrealva et al., 2006 specifies that in order to maintain the integrity of the adobe walls, both horizontal and vertical reinforcement are necessary c) Use of organic textile fibres (jute or coir) as natural, organic instead of polymer fibres – under plaster (suggested by Sikka and Chaudry, 2006) – yet to be tested, they suggest it only

Seismic retrofit is believed to have an effect only once ground shaking > 0.3g (Webster 2006). In-plane diagonal and X-Cracking at corners and doorways result from PGA levels as low as 0.10.2g. The relationship between damage and earthquake severity in relation to strength-based, stability-based and lack of retrofit as derived is presented by Tolles et al. (2002). Damage related to the use of the aforementioned retrofitting techniques includes cracking damage propagating from structural anchorage and cross-ties. Due to the weakness of earth as a structural material, low stress concentrations at these locations, which can hardly be avoided, generally lead to cracks and crushing of material. Anchorage can pull into wall thus being ineffective in adequately restraining out-of-plane motion or initiated cracks. Wall anchors (or tie rods) retrofitted with the intention of holding walls together with perpendicular walls or diaphragms are claimed by Tolles (1996) to be difficult to attach to adobe successfully because of the material´s weakness in shear and tension. In order to make the use of anchorage effectively, it is important to understand the behavior of earth around the anchors. Additional repair techniques


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Webster (2006) describes the seismic strengthening of a wall at O´Hara Adobe which was initially thought to be 90 cm thick, but was later found to consist of two separate leaves, each 30cm thick (Fig above). The wall such was filled with urethane-type foam of 48 kg/m³ between walls and superlightweight (1121 kg/m³) concrete under and beside the already existing bond beam. (Webster 2006) Alternative measures should be researched and tested. Difficult to assess effects of using different structures/


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1.2.3 Conclusions As well formulated by Morris (2006), material parameters on which analytical modelling can be based are often assumed without sufficient grounds. For instance, in Islam and Iwashita 2006, it seems that the characteristics of adobe blocks, instead of those of masonry, were used to model an adobe structure. As stated by Morris (2006), the critical material characteristics of earthen materials need to be identified and understood via shake table testing on stacked adobe blocks in order for analysis to be performed correctly. However, it is essential that consistency in testing procedures is maintained, so that results from different testing procedures can be compared amongst researchers. For instance, what lacks in various literature on earth buildings is a definition on the height-to-width ratio, moisture content or loading rate of compression specimens at the time of testing. Parametric studies should be based on the following (this list is not exhaustive) as variables: 1. Walls: Units: adobe, regularity in shape and geometry rammed earth is used, dimension of holes should be reported, presence of lifts, and material in between lifts Out-of plumbness of walls Opening, % of wall Minimum distance opening-corner Slenderness Bond/ring beam type and connection to roof Material composition No. Of leafs 2. Foundation Foundation material Foundation depth Foundation extends to height Foundation connection to wall present? 3. Roof Roof type Loading on walls Connection to walls


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1.2.4 References Arango Gonzalez, J. R. (1999) “Uniaxial deformation-stress behaviour of the rammed-earth of the Alcazaba Cadima”, Materials and Structures, 32 pp.70-74. Barrow, J.M., Porter, D., Farneth, S., Tolles, E.L. (2006) “Evolving Methodology in Seismic Retrofit: Stabilising the Las Flores Adobe”, Proceedings of the Getty Seismic Adobe Project Colloquium, The Getty Conservation Institute, USA, 2006, pp. 165-164. Bui Q.B. (2005) “Mise au point de léssai de compression simple sur mortiers de terre et pisés”. Rapport du Master de Recherche, ENTPE, 2005. Cancino, C.N. (2009) “Damage Assessment of Historic Earthen Buildings after the August 15, 2007 Pisco Earthquake, Peru” In collaboration with: Stephen Farneth, Philippe Garnier, Julio Vargas Neumann, Frederick Webster and Dina D’Ayala, The Getty Conservation Institute, Los Angeles, 2009. Chaudhry, C. (2007) “Evaluation of Grouting as a Strengthening Technique for Earthen Structures in Seismic Areas: Case Study Chiripa”, Graduate Program in Historic Preservation Theses (Historic Preservation), University of Pennsylvania, 2007 http://repository .unpenn.edu/hp_theses/68 last accessed 06 April 2010. Craigo, S.D. (2006) “´To Do No Harm´: Conserving, Preserving, and Maintaining Historic Adobe Structures”, Proceedings of the Getty Seismic Adobe Project Colloquium, The Getty Conservation Institute, USA, 2006, pp. 80-89. CORPUS (2010a), Traditional Mediterranean Architecture, “A7: Mud brick walls”, http://www.medacorpus.net/default.htm Meda CORPUS project, financed by the MEDA programme of the European Union, last accessed 06 April 2010. CORPUS (2010b), Traditional Mediterranean Architecture, “A8: Pisa wall”, http://www.medacorpus.net/default.htm Meda CORPUS project, financed by the MEDA programme of the European Union, last accessed 06 April 2010. Crosby, A. “Base Recording: Gathering Information” http://getty.museum/conservation/publications/pdf_publications/illustrated_examples2.pdf, last accessed April 2010 DÁyala and Bajracharya (2003) “Traditional Nawari house in Kathmandu Valley” HOUSING REPORT, Nepal, http://www.world-housing.net/, last accessed 06 May 2010.

DÁyala, D. (2006) “Seismic Vulnerability and Conservation Strategies for Lalitpur Minor Heritage”. ”, Proceedings of the Getty Seismic Adobe Project Colloquium, The Getty Conservation Institute, USA, 2006, pp. 120–134.

EEFIT (1982) “The Erzincan, Turkey Earthquake of 13 March 1992 – A field report by EEFIT”, Earthquake Engineering Field Investigation Team, The Institution of Structural Engineers, London


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EEFIT (2007) “August 15 Magnitude 7.9 Earthquake near the Coast of Central Peru” A field report by EEFIT”, Earthquake Engineering Field Investigation Team, The Institution of Structural Engineers, London EERI (2004) “Preliminary observations on the Bam, Iran, Earthquake of December 26, 2003”, Learning From Earthquakes, Earthquake Engineering Research Institute, Special Report, April 2004. Fujii, Y., Fodde, E., Watanabe, K.,Murakami, K. (2009) “Digital photogrammetry for the documentation of structural damage in earthen archaeological sites: The case of Ajina Tepa, Tajikistan”, Engineering Geology,Volume 105, Nos. 1-2, 23 April 2009, Elsevier, pp. 124-133. Gallego Roca, F. J. and Valverde Espinosa, I., (1993), “The city walls of Granada (Spain), Use, Conservation and Restoration”, 7th international conference of the study and conservation of earthen architecture, 24-29 October 1993 Silves, Portugal, pp.272 - 278. Ghannad, M.A., Makhshi, A., Mousavi Eshikiki, S.E., Khosravifar, A., Bozorgnia, Y., Taheri Behbahani, A.A. “A study on Seismic Vulnerability of Rural Houses in Iran”, First European Conference on Earthquake Engineering and Seismology (A joint event of the 13th ECEE & 30th General Assembly of the ESC), Geneva, Switzerland, 3-8 September 2006 Paper Number: 680 Ginell W.S., Thiel C.C., Tolles E.L., Webster F.A. (1995) “Seismic Stabilisation of historic adobe buildings”, Transactions on the Built Environment vol 15, 1995 WIT Press (Transactions of the Wessex Institute), www.witpress.com, ISSN 1743-3509, pp. 53-60. Gosain, N. and Arya,A.S. (1967 "A Report on Anantnag Earthquake of February 20, 1967" Bulletin Of the Indian Society of Earthquake Tecbnology (fn4), No. 3, September 1967 Graciani García, A. and Tabales Rodríguez, M. Á., (2003) “Typological Observations on Tapia Walls in the Area of Seville”, First International Congress on Construction History, Madrid, pp.1093-1106. Grunthal G. (1998) “European macroseismic scale”, Cahiers du Centre Européen de Géodynamique et de Séismologie, n.15, 1998. Halcrow (2003) “The Bam, Iran Earthquake of 26 December 2003”, Field Investigation Report Prepared By: Dr. Ali Reza Manafpour, Halcrow Group Limited Hardy, M., Cancino, C., Ostergren, G. (2006) “Introduction to the Getty Seismic Adobe Project 2006 Colloquium”, Proceedings of the Getty Seismic Adobe Project Colloquium, The Getty Conservation Institute, 2006, pp. xi-xiv. Hardwick, J. and Little, J. (2010) “Seismic Performance of Mud Brick Structures”, Engineers Without Borders UK, National Research Conference, February 2010. Huang Hanmin (1991) “Chuugoku minkyou no kuukan o saguru", Keiichirou Mogi, Kenchiku Shiryo Kenkyusha Co. Ltd., 1991 Hurd, J. (2006) “Observing and Applying Ancient Repair Techniques to Pise´ and Adobe in Seismic Regions of Central Asia and Trans-Himalaya”, Proceedings of the Getty Seismic Adobe Project Colloquium, The Getty Conservation Institute, pp. 101-108.


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ICOMOS (2005) “Heritage at Risk, H@R 2004/2005”, International Council on Monuments and Sites, Published by K G Saur, München, 2005. ICOMOS (2008) “Heritage at Risk, H@R 2006/2007”, International Council on Monuments and Sites, Published by E. Reinhold-Verlag, Altenburg, 2008. Islam, M. S., Iwashita, K. (2006) “Seismic Response of Fiber-Reinforced and Stabilised Adobe Structures”, Proceedings of the Getty Seismic Adobe Project Colloquium, The Getty Conservation Institute, 2006, pp. 11-22. Isik, B. (2006) “Seismic Rehabilitation Study in Turkey for Earthen Construction”, Proceedings of the Getty Seismic Adobe Project Colloquium, The Getty Conservation Institute, 2006, pp 101-108. Jaquin, PA, Augarde, CE, Gerrard, CM (2008) “Rammed earth construction techniques in Spain”, International Journal of Architectural Heritage. Volume 2 Issue 4, 2008. Jaquin, P.A. (2008) “Study of historic rammed earth structures in Spain and India”, The Structural Engineer. Volume 86 Issue 2. January 2008. JSEE (2004) Journal of Seismology and Earthquake Engineering, “Bam Earthquake of 05:26:26 of 26 December 2003, Ms6.5”, Editorial Summary: JSEE: Special Issue on Bam Earthquake / 1-3, Mohsen Ghafory-Ashtiany, JSEE Editor in Chief Kiyono, J., Kalantari, A. (2004) “Collapse Mechanism of Adobe and Masonry Structures during the 2003 Iran Bam Earthquake”, Bulletin of the Earthquake Research Institute, University of Tokyo, Vol. 79 (2004) pp. 157-161. Langenbach, R. (1989) „Bricks, Mortar, and Earthquakes, Historic Preservation vs. Earthquake Safety”, The Journal of the Association for Preservation Technology, Volume XXI, NO. 3 and 4, APTI 1989, pp 3043.

Langenbach, R. (2000) “Intuition from the Past: What We Can Learn from Traditional Construction in Seismic Areas”, Keynote Address, http://www.conservationtech.com/IstanCon/keynote.htm, 2000, last accessed 4 May 2000. Langenbach, R. (2004) “Soil dynamics and the earthquake destruction of the Arg-e Bam”, Journal of Seismology and Earthquake Engineering (JSEE),5 (4), 6 (1), 2004, p. 150. Langenbach, R. (2005) “Performance of the Earthen Arg-e-Bam (Bam Citadel) during the 2003 Bam, Iran, Earthquake”. Earthquake Spectra 21, Sp. Issue. S1 (2005), S345-S374, The Earthquake Engineering Research Institute, Oakland, CA, USA,. DOI:10.1193/1.2113167. Lopez, M., Bommer, J., Benavidez, G. (2002) “Vivienda de Adobe (Adobe house)” HOUSING REPORT, El Salvador, http://www.world-housing.net/, last accessed 16 April 2010. MaÏni 2004 Post Earthquake Assessment of Vaulted Structures at Bam, Iran http://www.earthauroville.com/index.php?nav=menu&pg=projects&id1=3&txt=text, last accessed April 2010 Minke, G. (2006) “Building with Earth” Birkhäuser, 2006, Basel.


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Morris, H. (2006) “New Zealand: Aseismic Performance-Based Standards, Earth Construction, Research, and Opportunities”, Proceedings of the Getty Seismic Adobe Project Colloquium, The Getty Conservation Institute, 2006, pp 52-66. Müller, U. 2002, Report entitled “Material analysis of adobe samples”, Chan Chan Peru, The Getty Institute, 2002. Navarro Grau, P.,Vargas Neumann, J., Beas,M. (2006) “Seismic Retrofitting Guidelines for the Conservation of Doctrinal Chapels on the Oyon Highlands in Peru”, Proceedings of the Getty Seismic Adobe Project Colloquium, The Getty Conservation Institute, 2006, pp 135-142 Neve, A. (1885) “Thirty Years in Kashmir” Edward Arnold, London, 1913, 316 pages. Röhlen, U., Ziegert, C. (2010) “Lehmbau Praxis” Bauwerk-Verlag, Berlin, 2010. th

Roselund, N. (1990) “Repair of cracked walls by injection of modified mud”, 6 International Conference on the Conservation of Earthen Architecture: Adobe 90 Preprints: Las Cruces, New Mexico, U.S.A., October 14-19, 1990, ed. Kirsten Grimstad, The Getty Conservation Institute, Los Angeles, pp. 336-41. Schroeder, H. (2010) “Lehmbau“, Vieweg + Teubner, Wiesbaden 2010. Sikka, S., and Chaudhry, C. (2006) “Upgrade of Traditional Seismic Retrofits for Ancient Buddhist Temples”, Proceedings of the Getty Seismic Adobe Project Colloquium, The Getty Conservation Institute, 2006, pp. 109-119. Tolles, E. L., Webster, F.A., Crosby, A., Kimbro, E.E. (1996) “Survey of Damage to Historic Adobe Buildings After the January Northridge Earthquake”, The Getty Conservation Institute, 1996. Tolles, E. L., Kimbro, E. and Ginell, W.S. (2002). “Planning and Engineering Guidelines for the Seismic Retrofitting of Historic Adobe Structures”. Los Angeles: The Getty Conservation Institute, 2002. Tolles, E. L. (2006) “Getty Seismic Adobe Project Research and Testing Programme”, Proceedings of the Getty Seismic Adobe Project Colloquium, The Getty Conservation Institute, 2006, pp. 34-41. Torrealva, D., Vargas Neumann, J., Blondet, M. (2006) “Earthquake Resistant Design Criteria and Testing of Adobe Buildings at Pontificia Universidad Catòlica del Perύ”, Proceedings of the Getty Seismic Adobe Project Colloquium, The Getty Conservation Institute, 2006, pp. 3-10. Vargas Neumann, J. (1993) “Earthquake Resistant Rammed-Earth Buildings” 7ª Conferência Internacional sobre o Estado e Conservação da Arquitectura de Terra, Silves, 1993 Vargas Neumann, J., Blondet, M., Tarque, N. (2006) “The Peruvian Building Code for Earthen Buildings”, Proceedings of the Getty Seismic Adobe Project Colloquium, The Getty Conservation Institute, 2006. Velkov, M., Olivier P. (1993). “Dynamic properties of Compacted Earth, as a building material” ENTPE, 1993. rd

Webster, F. A. (1995) “Some Thoughts on Ádobe Codes´”, Adobe Codes, 3 Edition, Bosque, NM, 1995 . Damage based selection of techniques

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Webster, F. A. (2006) “Application of Stability-Based Retrofit Measures on Some Historic and Older Adobe Buildings in California”, Proceedings of the Getty Seismic Adobe Project Colloquium, The Getty Conservation Institute, 2006, pp. 147-158. Ziegert, C. (2003) “Lehmwellerbau: Konstruktion, Schäden und Sanierung“, Technische Universität Berlin, Berichte aus dem Konstruktiven Ingenieurbau doctoral dissertation, Heft 37, Fraunhofer IRB Verlag ,Stuttgart 2003, pp. 283-292.


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2 PARTNER N° 4 - NTUA 2.1

CONSTRUCTION TYPES OF MASONRY, WALLS CONNECTION, FLOORS, ROOFS AND VAULTS

2.1.1 Construction types of masonry The construction types of masonry that are frequently met in historic structures in Greece are similar to those shown in your sketches for Italy. Nevertheless, in the pictures that follow, several types of masonry from various sites in Greece are depicted. You may use some of them to complete the respective section of the Deliverable. All pictures included in this file are taken from my personal archive. You may, therefore, refer to them without any further permission. Island of Chios (Medieval site of Anavatos)


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Island of Chios (Nea Moni)


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Clemoutsi castle (Peloponnese)

Same monument, different construction types


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Island of Samos (site of the ancient Gymnasium)


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Chalkis


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Orhomenos (Panagia Scripou Monastery)


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Dry stone masonry (Tiryns)


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Single-leaf stone masonry


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Monemvassia (south-east Peloponnese) Church in the Medieval site of Mystras (stone masonry with stones surrounded by solid bricks-the so-called “plinthoperikleisti”). Please note that this type of masonry is a three— leaf masonry. The interior leaf is made of ruble stone masonry. Poor quality filling material is placed between the two leaves. The same type of masonry is found in many Byzantine churches in Greece.


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2.1.2 Walls connection Even in the less elaborate structural systems, walls are interconnected with some care. Actually, larger cut stones are used for the construction of masonry in the regions where walls are crossing each other, as well as in the corners of the building. This is typical in buildings where no timber ties are provided. In timber reinforced buildings, quite often, the connection between walls is ensured by the timber elements (well connected in those regions, as shown in the pictures provided in the file floorsroofs). This is the reason why, the most critical (out-of-plane) failure does not take place exactly where walls meet but after the strong region of the connection.


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2.1.3 Floors and roofs In historic structures in Greece, typically, floors are made of timber. Due to the use of timber ties in most cases, there are several construction details in the connection between floor elements and timber ties. Furthermore, there is a vast variety of construction details in the region of cantilevers. Some examples are provided in the following photos.

All three alternatives illustrated in the figures are used. (a) The beams of the floor rest only on the interior longitudinal element of the timber tie, (b) the beams of the floor are extended to the outer face of the wall, thus resting on both longitudinal elements of the timber tie, (c) the beams of the floor protrude, in order to give support to balconies.


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Roofs are also made of wood. In several systems, due to the fact that earthquakes have to be sustained and as the diaphragm action of the roof plays a significant role in the seismic behaviour of the entire structure, there are roofs (a) that are stiff and form a 3-d bearing system and (b) that are carefully connected with the vertical elements (quite often, through the timber ties provided at the roof level).

The effort of the constructor to provide a 3-d bearing system at roof level is visible.

Roof and its connection with the timber ties. Damage based selection of techniques

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The case of the local structural system of Lefkada


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2.1.4 Vaults In the Greek Architecture, the shape of vaults and domes is normally that of part of a sphere or of a cylinder. Vaults are present in several historic structural systems in residential houses. This is normally the case for either the ground floor or the basement (typically used as warehouses or to host the animals of the family). In the upper storeys, typically, timber floors and timber roof are applicable. However, the most common case in which a system of vaults and domes are present is that of Byzantine and post Byzantine churches. There, the system of those curved structural elements give the possibility of creating interior spaces with large spans and significant height (i.e. spaces adequate for the worship of God).


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2.2


CHURCHES TYPOLOGIES

The main problem encountered by churches (covered with a system of vaults, domes and arches that transfer loads to vertical elements) is that the thrust of the curved structural elements, cause to the vertical elements horizontal deformations that are not negligible (even under vertical loads alone). Furthermore, the system of vaults and domes itself develops tensile stresses (Figure C2). This unfavourable state of stresses may become critical in case of an earthquake. Due to the thrust of the curved structural members, there is a tendency of vertical elements to deform out of their plane. Such a tendency is quite often more pronounced along the North to South axis, simply because (see Figure C1) there are more piers arranged along the east to west axis. The result of this kinematic scheme is the opening of cracks in arches supporting domes and cupolae, as well as shear and out of plane damage of piers supporting the system of curved structural members. Such pathology is typically observed to Byzantine monuments (Figure C6,C9). This is confirmed also by two facts (a) in several cases, the cental cupola of Byzantine churches is reconstructed after severe damage of the drum due to an earthquake. This is easily explained by this tendency of vertical elements to move outwards (Figure C7, C8). Thus, the supports of the cupola are moving outwards as well. As the cupola itself is very stiff, the elements that suffer are the piers of the drum. In they fail, the cupola loses support and may fall in the interior of the church, as actually reported in several cases and (b) the behaviour observed after earthquakes has led people to intervene in a way to reduce the effects of the above described mechanism. Actually, this is the case in the two major Byzantine monuments presented in Figures C4, C5, buttresses were added to enhance the stiffness along the N-S axis.


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DAMAGE EXAMPLES

E1: Example of the effect of poor quality construction type of masonry built with poor quality materialsOut-of-plane collapse of the exterior leaf of a three-leaf masonry wall. Rubble stone masonry built with clay mortar (Earthquake of Andravida-Peloponnese, 2008)

E2: The state of the entire building (in addition to the poor quality of masonry) is due to the lack of a roof that would be able to connect the walls among them. In-plane bi-diagonal (shear) cracks have also opened.


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E3: Typical collapse of the corner of a building due to out-of plane bending of the walls (seismic action oblique with respect to the two main axes of the building). The concurring effect of the low quality of masonry is visible (Andravida, 2008).

E4: Poor quality masonry. Partial collapse of the external leaf of masonry wall, after the occurrence of inplane shear crack (Alkyonides, 1981)


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E5: Out-of-plane collapse of walls. Defectively connected roof and walls (Alkyonides, 1981)

E6: Out-of-plane collapse of a wall. Observe in the left hand side of the picture that the collapse extended to the opening (located very close to the corner of the building). Due to the lack of adequate connection of the floors to the walls, the collapse extended partly to the ground floor as well. The complete collapse of the ground floor wall was, most probably, limited by the wall of the adjacent building that collapsed (with the exception of one wall of visibly low quality).


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E7: The (short) ties between longitudinal and transverse wall, arranged at the level of the floor, was (expectedly) not able to prevent the out-of-plane collapse. This closer photo allows us to observe that (reinforced?) concrete slabs were constructed at floor levels. The distance between the end of the roofing and the protruding part of the slab indicates that the slab was supported by the collapsed wall. The effect (perhaps negative) of the slabs cannot be assessed just by visual inspection (Andravida, 2008)


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E8: lack of adequate connection between floor and walls (that would allow each storey to behave as a box) allowed the cracks to develop along the entire height of the portions of masonry between the bottom of the upper opening and the top of the lower opening (Andravida, 2008)

E9: The effect of inadequate connection between floor and walls is visible also on this photograph (Andravida, 2008)

E10: Out-of-plane partial collapse of poor quality masonry (Andravida, 2008)


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E11: Separation of the transverse wall from the longitudinal one, due to the out-of-plane bending of the former. The sliding of the roof (out of the perimeter of the building) due to the lack of connection with the walls is apparent (Andravida, 2008)

E12: Typical bi-diagonal cracks due to in-plane shear (Andravida, 2008)


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E13: Partial collapse of (poor quality) masonry wall out of its plane. Its disintegration was aggravated by the simultaneous in-plane shear that caused bi-diagonal cracks (Andravida, 2008)

E14: Separation of wall due to out-of-plane bending. The quasi linear vertical crack insinuates that the connection between the walls was defective.


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2.4


TIMBER REINFORCED STRUCTURES IN GREECE: 2.500 B.C-1.900 A.D. Elizabeth Vintzileou

ABSTRACT The survey of numerous monuments and historic structures in Greece-a country situated in the most earthquake prone area of Eastern Mediterranean-has revealed a systematic and continuous through-centuries use of timber elements within masonry. The extent of the use of timber in the structures, the contribution of the timber to the overall structural system, the specific measures taken to protect timber from decay and, hence, the efficiency of the developed structural systems do present a vast variety, associated with social and economical factors. This extensive use of timber makes it legitimate to assume that our predecessors were aware of the effect of timber reinforcing systems on the seismic behaviour of structures. This paper provides information on the use of timber in structures in Greece ranging from the Minoan Crete-2.500 years B.C., to Akrotiri, Thera-16th century B.C., to Byzantine churches and Monasteries, and finally to more than 70 urban nuclei within the country-developed in the 18th and 19th centuries.

1. INTRODUCTION For any historic structure, the bearing system, developed to withstand and to safely transfer actions to the Earth, constitutes an integral part of the structure and hence is among the values to be preserved for the structure. Throughout Greece, the work of Archaeologists, Architects and Engineers in numerous archaeological sites, in individual monuments, as well as in historic centres has brought to light numerous structural systems developed by smaller or larger communities over the course of almost 5.000 years (Figure 1). The level of sophistication of each structural system depends on the use of each individual building, on the social organization of the community, on its wealth, etc. It is, however, remarkable that independently of the local conditions under which these structural systems have been developed, a systematic use of timber elements is recorded throughout the history of civilization in Greece. 2. THE MINOAN PALACES AND VILLAS The oldest architectural remains found in the island of Crete date back to the late Neolithic era (5th millennium B.C.); a complex of residential houses, dating back to the 4th millennium B.C., was brought to light thanks to the excavations by Evans (1). The early Bronze Age is marked by intensive activity in various fields in Crete. A characteristic specimen of residential settlement of that period (termed as the Pre-palatial period) was excavated in Vassiliki (Ierapetra). The settlement, organized as a functional entity, bears witness to the high level of architectural design reached by the Minoans already in the 2nd millennium B.C. Excavations in major sites (such as Knossos, Festos, Malia and Zacros), as well as in numerous other locations throughout the island prove that during the 2nd millennium B.C. there is a very dense network of Damage based selection of techniques

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settlements. Furthermore, there are clear signs of extensive destruction of buildings and entire settlements due to earthquakes. Tsakanika 2 documents a comprehensive study of the bearing structures of palaces and villas (noble houses) in the Minoan Crete of the late Bronze Age. The systematic use of timber elements is also evident at other locations including Mycenae and Thivai. Tsakanika’s work (2) constitutes a corpus of more than 14,000 images that document the structural systems of the studied buildings at more than 10 locations. The available documentation points to the use of timber as both horizontal and vertical load bearing elements including main and secondary beams, floor joists, roofs, staircases, door and window lintels and frames, pillars, timber framed piers filled with rubble stone masonry, along with vertical and horizontal reinforcing of rubble- or cut stone-masonry walls. Many of these timber elements do not survive to the present day, but their existence, location and dimensions are evidenced by vertical, horizontal or oblique holes in the masonry. The use of cypress wood was identified in various sites (including Knossos). Nevertheless, the use of other types of wood cannot be excluded. As even a concise presentation of the available documentation is impossible, in this paper, only some illustrations (Figures 2 - 6) are here reproduced from Tsakanika (2). Some key remarks regarding the studied structural system are repeated here: 1. Economy in constructive effort is observed. The Minoans were using local materials to avoid massive transport from other locations (Tsakanika 2). Nevertheless, stronger stones were used in exterior walls, as well as in pavements. Stones are cut only on the exterior faces of structural members, as well as in faces that are in contact with timber elements. Needless to say that an exemplary organization of the site is a prerequisite for such a sensible use of local and imported materials. 2. A peculiar characteristic of the Minoan architecture is that transversely meeting masonry walls are not interconnected. As shown in Figure 5, it seems as though the perimeter walls parallel to one of the main directions were constructed first, followed by those parallel to the other main direction. The integrity of the system was ensured by timber framed piers, arranged at all corners and at free-ends of walls. Rubble stone masonry fills the space between consecutive stronger vertical elements. 3. Special care is given to the foundation of the bearing system. All structural members were made of cut stones. Also, piers between openings are resting on cut stones (Figure 6). The arrangement of those stones coincides with critical locations (such us free ends of walls, intermediate locations where masonry is subjected to high loads, locations of timber frames of doors, etc.); it seems therefore legitimate to assume that the entire plan of the building, as well as the scheme of the bearing system were fully designed before the commencement of the construction process. 4. The systematic use of timber or timber framed elements at critical locations (such as locations of high vertical loads, in corners and free-ends of walls, as well as in piers between openings), along with the elaborated system of forming those elements that are interconnected at floor and roof levels, insinuate that the Minoan technicians were aware of the fact that their constructions had to face seismic events. Even severe damages and partial collapse of the (rather weak) rubble stone masonry would not cause collapse of the entire building, since the (stiff and strong) timber “skeleton” of the structure was able to resist the seismic actions and to bear vertical loads until rubble stone masonry was


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repaired after an earthquake. It should be noted that a structural system that follows similar design logic is still in use on the island of Lefkada.

3. STRUCTURAL SYSTEMS IN PREHISTORIC TOWN OF AKROTIRI IN THERA Akrotiri, a flourishing town on the island of Thera-Santorini, was destroyed by a volcanic eruption circa 1.500 B.C. The construction system of the site in Akrotiri (preserved under volcanic material), almost contemporary of the structural system in Crete, was exhaustively studied by Palyvou 3. Similarly to palaces and villas in Cretan sites, walls and piers in Akrotiri are founded on the rock. In numerous cases, the rock is worked with the purpose to form a horizontal plane; in other cases, a cut stone is placed between the rock and the masonry element (Figure 7). In Akrotiri, 2- and 3-storey buildings are mainly made of rubble stone masonry. Better quality masonry is apparent in zones that are critical for the bearing capacity of the structure, such as the corners of the building (meeting walls are tied and, hence, box action of the building is ensured), around openings (reinforcement of walls that are weakened because of the openings), and at free-ends of walls (sensitive to out-of-plane actions due to the lack of transverse collaborating wall). In those locations larger dimension stones with elaborated faces are used. Rubble stone masonry is systematically reinforced using timber ties: As a rule, nets of horizontal timber elements are incorporated within the masonry at various levels; there are, however, some cases of vertical timber elements that will be referred to separately. As shown in Figure 8, branches of trees were used to form the net of horizontal wooden elements. Normally two longitudinal timber elements are running around the entire room and, quite often, around the entire building. In some cases, in the connection zone between a longitudinal and a transverse wall, three timber elements are arranged. Transverse timber elements are resting on the longitudinal ones; they are either perpendicular to them or oblique (typically, in the corners of the buildings). As the available length of branches could not cover the entire length of walls, longitudinal timber elements consist of several branches, either placed one next to the other or spliced. Horizontal nets of timber elements are arranged typically close to the lower level of the wall, below openings and at the level of lintels. In some cases, a fourth net of timber elements was identified at floor level. As the imprints of wooden elements on the volcanic ash were not preserved, available information on the types of wood used in the buildings is limited. Although various kinds of trees were identified in other locations on the island of Thera (namely, Tamaris, Pistacia lentiscus L., Olea europae, Phoenix Dactylifera I., etc.), there is no evidence to exclude or certify their use in Akrotiri. Vertical networks of timber elements were identified in three buildings in Akrotiri, thanks to the holes left within the volcanic material when the wood disintegrated. Note that only parts of some of the buildings in Akrotiri have been excavated. Figure 9 shows the restored façade of Xeste 2, where the disintegrated timber elements were substituted by reinforced concrete ones; the arrangement of a net of (rectangular in section) horizontal and vertical timber elements is apparent. Unfortunately, as this wall was discovered and restored during the early stage of excavations (when the structural system of Akrotiri was unknown to Archaeologists), no information was gathered regarding the length of timber elements or their connections. The interior of Xeste 2 is not yet excavated. Therefore, there is no information as to whether a similar network of timber elements is arranged on the opposite face of the wall. Nevertheless, one may assume that this is the case, on the basis of similar findings in other (partly excavated and not yet restored) buildings. The south exterior wall of Xeste 3 (Figure 10a) allows for the system of vertical nets of timber elements to be identified and represented (Figure 10b). Damage based selection of techniques

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Among the numerous interesting findings related to cut stone masonry walls, pillars, floors and staircases, it is of special interest to focus on the 3D timber frames of exterior and interior doors and windows (Figure 11). The effort of the constructors in Akrotiri to form timber frames stiff enough and able to safely transfer vertical loads is apparent. Other than that, the arrangement of series of wide openings around the interior courtyard of the buildings allowed for lighting and for organization of family life within the house. In conclusion, it can be stated that, although there are some similarities with the system developed by the Minoans, the structural system of Akrotiri is locally developed. Timber ties arranged within rubble stone masonry served as reinforcement of the low tensile strength masonry. Furthermore, the horizontal and vertical timber ties together formed a robust 3D system which confined and so enhanced the deformation capacity of the masonry. The timber elements were also able to safely withstand vertical loads, in case masonry was damaged or even partially collapsed, thus allowing buildings to survive until masonry was repaired. Finally, the elaborated 3D system of timber frames in multiple windows and doors constitutes a sophisticated solution of substitution of masonry with the purpose of serving functionality while respecting the rules of “seismic design”. 4. TIMBER TIES IN BYZANTINE ARCHITECTURE The traces of the use of timber reinforcement in buildings are found in numerous structures (residential houses, churches and towers) of the Byzantine era. It is interesting to observe that timber ties are widely known under the term of “imandosis”, which comes from the Greek word “imas”-genitive “imandos”: strap. In the 9th century dictionary of Patriarch Photios 4 and the 10th century dictionary of Souda 5 , “imandosis” is defined as a tying system ; it ties together timber elements embedded in buildings. The beneficial effect of timber ties is recognized and mentioned even in texts not related to construction. For example, St. John Chrysostom (349-407 A.D.), in his epistle to the people of Antioch (Homily VI)6 writes: “…for what the stay-beams (εν ταις οικίαις των ξύλων αι ιμαντώσεις-literally: in houses, timber strappings) are in houses, that rulers are in cities; and in the same manner as if you were to take away the former, the walls, being disunited, would fall in upon one another…(αν εκείνας ανέλης, διαλυθέντες οι τοίχοι συμπίπτουσιν αλλήλοις αυτόματοι)”. Among the numerous examples of the use of timber in the Byzantine architecture, two cases are selected for this paper, namely the Church of Panaghia Krina (in the island of Chios) and the Doheiarion Monastery in Mount Athos. The church of Panaghia Krina (Figure 12a), built in the 12th century A.D. has survived several earthquakes. The monument being in a critical state, the Hellenic Ministry of Culture has funded a research program (Vintzileou et al. 7) with the purpose to investigate the structural system of the monument, to assess the available margins of safety and to explore possible intervention techniques. Within the program, the construction type of masonry was also investigated, mainly through boroscopy, a technique consisting in drilling a hole of small diameter in masonry and observing the interior of masonry using an optical fibre device. The investigation proved that the monument was reinforced by means of timber ties at five levels within the height of the walls as shown in Figure 12b. Figure 12c shows the arrangement of timber elements (both longitudinal and transverse) in one of the levels. One of the main problems that arises when timber ties are identified within masonry in monuments is that timber elements are completely (or, even worse, partly) disintegrated. As in the normal case timber ties are located away from masonry surfaces (for reasons of protection from humidity changes), it is extremely difficult, if not impossible to replace the rotten wooden pieces and to ensure connection between longitudinal and transverse timber elements. Quite often, substitution of timber ties by external or internal metal ties is attempted. Nevertheless, Damage based selection of techniques

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metal ties can only replace the longitudinal timber elements. Transverse connections, provided in the original timber ties at distances not exceeding one to two times the masonry thickness, cannot be substituted and connected to the longitudinal metal ties. Although research on this subject is ongoing, the urgent need to preserve historic structures and monuments imposes alternative solutions to be invented and applied. The problem is solved on a case-by-case basis, by enhancing the bearing capacity of the masonry itself (e.g. through grouting), by enhancing box action of the building by providing (preferably, timber) diaphragms at floor and roof levels, etc. The Doheiarion Monastery in Mount Athos (Figure 13) was founded in the 10th century. The investigation of the complex of buildings 8 has shown that timber ties (both visible and invisible) are used in the Katholikon (main church), in the cells, as well as in the tower of the monastery. Figure 14 shows the levels at which timber ties were identified. One may observe that (visible) timber elements are used as ties in the origins of arches and vaults, as well as within masonry along the perimeter walls in the form of timber ties (imandosis). The fact that the Constructors of the monastery were aware of the importance of timber elements is proved also by their care to protect them from humidity. Figure 15 shows a detail of the timber tie located within the masonry of the cells: Below timber elements, a recess was formed using stones. This recess (20 to 30 mm deep) covered with lime mortar, plays the role of drainage for the timber elements, thus keeping their humidity constantly below the biological attack level. Finally, it is very interesting to look at the findings concerning the tower of the monastery (Figure 16): A system of horizontal timber ties was detected at floor levels, as well as at intermediate levels (in the bottom of openings). At intermediate levels, the connection among longitudinal timber pieces is ensured by means of diagonally placed stiffening elements. At floor levels, timber ties (located within the thickness of masonry) are connected to the timber beams of the floors. Timber pavements fixed onto the floor beams ensure a diaphragm action of the floors, thus forcing the walls to deform jointly in case of an earthquake. The concern of the Constructors about the seismic behaviour of the tower is also proven by the fact that, as shown in Figure 16b, the floor beams are positioned along the x- or along the y-direction every other floor. In this way, a uniform behaviour of the tower is sought, independently of the predominant direction of the seismic motion. 5. HISTORIC STRUCTURAL SYSTEMS (18TH AND 19TH CENTURIES) The survey of historical structural systems throughout Greece has proven that practically in all of them (more than 70 historical structural systems) timber reinforcement (made of wood from olive or chestnut trees in many cases) is used within the thickness of masonry (Figures 17 and 18). The typology of timber ties (location, dimensions of wood elements, arrangement within masonry thickness (Figure 19) and along the height of walls, splices in longitudinal timber elements (Figure 20), connections between longitudinal and transverse elements (Figure 21), etc.), their effect on the seismic behaviour of buildings, the typical pathology of those systems, as well as possible intervention techniques were investigated within a research program (Vintzileou 9). The main findings of that research (that are in accordance with the observed behaviour of historic structures) confirm the positive effect of timber ties in (moderately) enhancing the compressive strength of masonry due to confinement, in significantly enhancing the deformability properties of masonry, thus permitting the buildings to sustain large deformations (due to earthquakes or land slides) without disintegration and collapse. Furthermore, thanks to the presence of timber ties acting as reinforcement to the masonry, the action effects on Damage based selection of techniques

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masonry due to seismic events are reduced, while at the same time the respective bearing capacities of masonry elements in shear and in out-of-plane bending moments are increased by as much as up to an order of magnitude. As a final example of use of timber in historic structures in Greece, mention should be made of the structural system developed (and still in use) in the Ionian island of Lefkada, situated in the 10 most earthquake prone region of the country. That system (Vintzileou et al., ), seems to fulfill most of the requirements of current Codes for the conceptual design of earthquake resistant structures: (a) Symmetry in-plan and in-elevation is ensured, (b) Mass and stiffness are concentrated in the ground floor (made of rubble stone masonry), while in the upper storey(s) mass (but not stiffness) is reduced thanks to the construction of timber framed walls. The peculiarity of this structural system, which has sustained several strong earthquakes, lies in the secondary timber structural system provided to all buildings (Figure 22). As proven by survey and calculations, the secondary system (too flexible to contribute to the seismic behaviour of the building) is able to safely sustain vertical loads, in case the masonry of the walls between ground and first floor is severely damaged or even collapsed due to a seismic event. Thus, the structure remains safe and gives the population the time that is necessary for repair or reconstruction of the damaged masonry.

6. CONCLUSIONS From this (though inexhaustive) description of structural systems developed in Greece through centuries and millennia, the following observations apply : 1. Constructing has always been an important activity of the inhabitants of this part of the globe too. To ensure safe shelters for their private and social activities, our predecessors invented clever structural systems able to sustain the actions imposed by nature. 2. The use of timber (in various alternative forms and arrangements) in buildings seems to be continuous through many centuries. It was a common belief that the high tensile strength of wood (as compared to the extremely low tensile strength of masonry) contributes to the enhancement of the bearing capacity of masonry elements; the use of the term “imandosis” proves that they knew by experience that timber elements are able to tie together the perimeter walls of buildings, the leaves of masonry within the wall thicknesses, the floors and the roof to the walls, etc. These timber ties enhanced the “box action” of the masonry structures, a major characteristic of safety against earthquakes. These well-tied boxes are less deformable and, hence, less liable to disintegration and to collapse than are other “open” forms of structures. 3. It is fascinating, however, to observe that the respect of the “rules” for satisfactory seismic behaviour did not lead to uniformity in architecture. On the contrary, even the few examples presented in this paper show a vast variety of architectural forms; the respective structural solutions (obviously conceived together with the architectural forms) are far from being conventional and conservative. To mention the example of Minoan villas and that of residential houses in Akrotiri, large open spaces are created within the buildings. In those cases, three-dimensional timber structures are provided; they enhance the bearing capacity and the stiffness of masonry, while serving functionality and allowing for innovative architectural design.


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4. It has to be noted, however, that although timber is quite durable under certain conditions, timber elements within masonry are not everlasting. This is one of the major problems the modern Structural Engineer has to face in the effort to preserve timber reinforced historic structures. Although several solutions are available, the problem still asks for more alternative solutions and for better documentation of the available ones.


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REFERENCES 1. Evans A.J.: “The palace of Minos: a comparative account of the successive stages of the early Cretan civilization as illustrated by the discoveries at Knossos, Volume 1: The Neolithic and Early and Middle Minoan Ages”, McMillan and Co., Ltd., London, 1921, 778 pp. 2. Tsakanika E.: “The structural role of timber in masonry of palatial type buildings in the Minoan Crete”, Doctor Thesis, National Technical University of Athens, 2006 (in Greek). 3. Palyvou C.: “Akrotiri-Thera: The Art of Construction”, Library of the Archaeological Society of Athens, No 183, 1999, 491 pp. (in Greek) st

4. Photios the 1 , Λέξεων Συναγωγή (Collection of Words), Volume B (E-O), Publisher ΚΑΚΤΟΣ (Cactus), ISBN : 9603825697, 2004, 367 pp. (in Greek) 5. Suda on line iota 332 (Himantes-straps) http://www.stoa.org/ 6. St. John Chrysostom, Archbishop of Constantinople “The Homilies On the Statues; or to the people of Antioch”, Members of the English Church, reprint from the book published in Oxford, John Henry Parker, J.G.F. and J.Rivington, London, MDCCCXLII, p. 117. 7. Vintzileou E.: “Panaghia Krina in Chios: Identification of timber reinforcement, assessment of current state and related interventions”, Research Report, 2006 (in Greek). 8. Touliatos P.: “The Doheiarion Monastery in Mount Athos-The Architecture of the Katholikon and the Tower”, National Technical University of Athens, 2009, 134 pp. (in Greek). 9. Vintzileou E.: “The effect of timber ties on the behaviour of historic masonry”, ASCE, Journal of Structural Engineering, Vol.134, Issue 6, pp.961-972, June 2008. 10. Vintzileou E., Zagotsis A., Repapis C., Zeris Ch. : « Seismic behaviour of the historical structural system of the island of Lefkada, Greece”, Construction and Building Materials, 21, pp. 225-236, 2007


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EFFECT OF TIMBER TIES ON THE BEHAVIOUR OF HISTORIC MASONRY


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TIMBER REINFORCED MASONRY SYSTEMS IN GREECE

(The information provided in this file is taken form a Research Report, National Technical University of Athens NTUA/Earthquake Protection and Planning Organization EPPO. 2005. “Investigation of timber reinforced masonry.” Research Rep., E. Vintzileou, P. Touliatos, and E. Tsakanika, eds. in Greek) (1) For historical aspects of the use of timber in constructions, please see files timberreinforcedtext, timberreinfrocedfigures1 and timberreinforcedfigures2. (2) For typology, please see my paper in ASCE, Journal of Structural Engineering. Please note that timber ties are normally located in rather poor quality masonry (adobe, rubble stone masonry, three-leaf stone masonry, etc.)


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Figure 1: A typical timber reinforced masonry system (Psichis, Tsouras, 1992) (3) Some pictures useful for illustrating the system are included here.

Figure 2: Building in Mount Pelion (Kizis, 1995)

Figure 3


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Figure 4: Siatista, Timber reinforcement around openings (Melissa, Vol. 7)

Figure 5: Achaia, Timber reinforcement around openings (Melissa, Vol. 4)

Figure 6: Connection of timber elements in the corner of a building


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Figure 7: Connection of timber elements in the corner of a building (sketch by P.Touliatos)

Figure 8: The same. Kastoria (Melissa, Vol. 7)

Figure 9: The same. Paleos Panteleimon (Macedonia)

Figure 10: Splicing of longitudinal timber elements, Lesbos


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Figure 11: Failed splice Paleos Panteleimon, Macedonia)

Figure 12: Splice of longitudinal timber elements (ibidem)

Figure 13: Splices, Veroia (Melissa, Vol. 7)


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Figure 14: Splice, Metsovo (Melissa, Vol. 6)

Figure 15: Connection between longitudinal and transverse timber elements, Metsovo (Melissa, Vol. 6)

Figure 16: Connection between longitudinal and transverse timber elements (sketch by P.Touliatos) (4) The structural role of timber ties is summarized in the figure that follows :


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The tie beam arranged at floor and roof levels allows for uniform distribution of vertical loads to walls.

The net of longitudinal and transverse timber elements ensures connections between the leaves of masonry in its thickness.

As the word itself indicates, tie beams provide enhanced tying of walls among them. Thus, their out-of-plane collapse is prevented or significantly delayed, as compared to unreinforced masonry walls.


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The capacity of the building to withstand differential settlements is enhanced.

Timber ties ensure the connection between perimeter and interior bearing walls (Prespes, Melissa, Vol. 7)


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Timber ties provide strengthening of the regions of openings

Timber ties act as flexural and shear reinforcement Timber ties increase the deformability of masonry

(4) Typical pathology of timber reinforced systems Damage based selection of techniques

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The main problem of timber reinforced systems is the in-time degradation of wood.

Furthermore, some construction errors are recorded in several structures. Those errors increase the vulnerability of timber reinforced systems.

When transverse timber elements are simply resting on the longitudinal ones, connection of the two exterior leaves of masonry may not be sufficient.


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Timber ties do not continue in the corner zone of masonry. Thus, their tying role cannot be activated and cracking (due to out of plane bending) cannot be prevented.

Poor splicing detailing: When the nail that connects the two wooden elements is corroded, the tying action of timber ties is lost.


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Arrangement of all splices along a vertical line predetermines the location of cracks. (6) Timber reinforced systems pose rather difficult problems, when their preservation is sought. The main problem is that it is quite difficult to replace or to substitute rotten timber ties that are-quite often-located away from masonry faces and, hence, difficult to reach.

REFERENCES Psichis Ph., Tsouras B.: “Adobe constructions”, Dimploma Lecture, Faculty of Architecture, NTUA, 1992 (Supervisors: P.Touliatos, I.Ephessiou). Kizis J.: “The Art of Construction inPelion”, Peiraios Bank, 1995 Greek Traditional Architecture, 8 volumes (various authors), Publ. Melissa, year: from 1982 to 1998


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INTERVENTION WITH USE OF RC TIE BEAM

The negative effect of the RC addition to the building.


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An RC tie beam is constructed under the opening. Disintegration of the pier and horizontal sliding thereof is observed.


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Interaction between the stiff church and the less stiff bell-tower.


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2.8


DAMAGE ABACUS :

2.8.1 Timber reinforced masonry - Decay of wood

a- Undamaged stage Three-leaf masonry wall with double timber lacing at floor level.

b-Longitudinal cracks in timber elements. Although longitudinal cracks do not constitute a failure in themselves, they are a sign of volume changes of wood. This may lead to loosening of connections of timber elements.

c-Biological attack and disintegration of timber Humidity over 20% and significant humidity changes favour biological attack that may lead to complete disintegration of timber elements and of the entire tie system. As a result, masonry is weakened and the occurrence of damages becomes more probable d- Start of the collapse Decay of inner timber lacing leads to overturning of the upper masonry assemblage and start of the collapse of the inner core constructed with rubble stone and poor or decayed mortar.


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(24)


e- Collapse development Progressive overturning leads to the destruction of the decayed outer timber lacing, further collapse of the inner core and separation of outer leaves.

2.8.2 Timber reinforced systems - Construction errors a- One or more timber ties are not located in the same level in perimeter and interior bearing walls Timber elements do not function as a tie, but as simple reinforcement to the masonry walls. The lack of connection between meeting walls may result to out-of-plane collapse of them.

th

Mykonos, 19 century: No connection between timber ties of the transversely meeting walls. Defective connection between walls.

b- Lack of connection between timber elements The two longitudinal timber elements are not spliced. Due to corrosion of the nail that was keeping the two timber elements connected or due to failure of the nail due to previous actions, the two elements are disconnected. Therefore, the tie is not longer active. As a result, timber elements cannot prevent cracks to propagate.


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c- Inadequate transverse connection of longitudinal timber ties The outer face of the poor quality masonry has collapsed because of inadequate connection between longitudinal and transverse timber elements.

d-Location of poor quality connection in the same location vertically. A common mistake that enhances the vulnerability of the system. Decay or failure of the connections allow cracks to propagate.


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e. Discontinuity of timber ties over arched openings Timber tie is no active.


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3 PARTNER N° 8 – UBATH 3.1

COLLAPSE MECHANISMS AND CRACK PATTERNS OF HERRINGBONE PATTERN MASONRY VAULTS


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3.2


FRP REINFORCED MASONRY ARCHES


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3.3

FACADES MECHANISMS

Mechanism

Load factor j i

2

r hs 2 l j sb 3 l 1 r

Ti L 1 2

( 0 ), j

j

hs

j

TN 2

kL

hs j

i 1

T

hs j i

j

1 2

LTi j i

Ti i 1

kL j

j i i 1

is the number of internal bearing walls orthogonal to the façade, and effectively connected to it as to provide restraining action due to friction

A j

i 1

Ti 2 L 2

(

)

( 0), j

hs 2 j tan 2 j

hs

hs tan 3

j Ts

LTi j

1 2

i

i 1

Ti

j

(

)

kL

TN 2

j

hs j

Ti

T

hs j

i

i 1 j

hs2 3 j tan 3

j

kL j

j

i

i 1

is the number of edge party walls orthogonal to the façade under exam which can provide restraining action

B1

as above Ts

thickness of party walls and internal bearing walls j

i 1

Ti 2 L 2

(

)

( 0), j

hs 2 j tan 2 j

hs

hs tan 3

j Ts

LTi j

1 2

i

i 1

Ti

j

(

)

kL

TN 2

j

hs j

Ti

T

hs j

i

i 1 j

hs2 3 j tan 3

j

kL j

j

i

i 1

as above as above

B2 TN jf

Tj j2 2 2

( 0 ), j

C

j 1

k

2

jhh 3

j i i 0

=tan

jf

js

=tan

js

integer identifies the load bearing wall

Tmj Tmj 2

2

j 1

k

j i i 0

jhh 3

2

Tj

js

2

jf

k

js

(1

jf

)

j i

js i 0

=(0,1)

j i

j

Tj j2 2 2

j 1

(1

L

i 1

( 0 ), j

j j

LT mj 3

2

L

j 1

Lj kL khs tan

TN js

2

T N T j hs 2 j j2 3 2 2

jf

2

Tj

jf

kL

hs 2

)

r hs 2 l j sb 3 r l 1

2 2 khs tan 3

jkh s

L 2

2 hs tan 3

j 1

j i

j i 1

j 1

j i

j i 1

as above

D

L

width of facade in between party walls.

Tmj

average thickness of wall over height of overturning portion


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2



j i

Ti 2 L var 1 2

hs

hop

hs

( 0 ), j

r 1 2 l j sb 3 l 1 r

kL var

1 2

k j

j

hs Lvar

Ti j i i 1

j

TN 2

hs j

Ti

T

hs j i

i 1

j

j i i 1

as above as above = (1,2) is the number of vertical discontinuities within the façade non coincident with the façade edges

E

= (1,2) integer

Ti Ti 4

=(0,1) provides the number of active side connections

Tk

Ti TN Ti hu hv 2 hv 1 Ti T j 4 2

k

h

u

hv 6 hv

F

1 4

Ti

2

Ti 2

Tj

Tk2

Tk

khs Tk

2sbhv 3l k Tj

1 2

l r0

1

l

r1

r1

hv

r0

hi

l

r2

1 l r1

r2

r1

hj

1 T j2 k

Tj

1

hv

hi

hj

r0, r1, r2, number of courses above upper hinge, middle hinge, lower hinge respectively real number (0,1) hv height of portion of wall subjected to mechanism

l

Tu

Ti 4

kL l 2i 2

, hi

l

G

L hi 2tg

The index

i

valid for

Tu

2

Ti

L l

4

l

L Tu 8

Ti

2l l

L

L2

r

sb Tu

Ti l 1

2

l r

r

l

s b l l

1

r

2

5 Ll L kL 5l 2i 3l l

identifies quantities associated with internal bearing walls

Mechanisms and load factors for façade failures (D’Ayala and Speranza, 2003) D’Ayala D., Speranza E. (2003). Definition of Collapse Mechanisms and Seismic Vulnerability of Historic Masonry Buildings. Earthquake Spectra 19(3): 479–509.


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3.4


MECHANISMS FOR ABACUS

Failure mechanisms of facades (D’Ayala, 2009) D’Ayala D. (2009). Seismic Vulnerability and Conservation Strategies for Lalitpur Minor Heritage. In Proceedings of the Getty Seismic Adobe Project 2006 Colloquium, pp.120-134.


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4 PARTNER N° 10 - ENA 4.1

LOCAL CONSTRUCTION PRACTICES AND DAMAGE MECHANISMS

4.1.1 Introduction 4.1.1.1 Background In the field of traditional rural architecture, there are different types of implantation: douars in the mountains, ksour and casbahs. Douars, groups of single-storey houses, are found in the valleys of the whole of the north, centre and mountain ranges of Morocco. Ksour are fortified collective implantations inside a town wall with a single gateway and a regular layout of narrow streets. Houses with a central courtyard are usually built on two levels and are found in the pre-Saharan valleys and the oases in the south. The casbahs are fortified single-family buildings of several floors, inhabited by the tribal headman. They are found in the pre-Saharan valleys and the oases in the south. The construction materials and techniques used include earth, pisé and adobe, and stone masonry for bearing walls. Timber and reeds are used to build the floors, with rammed earth. Decorative elements are found only at the top of casbahs and on some doors of the ksour.

Ksar Ait-Ben-Haddou Ksar Ait-Ben-Haddou was added to Unesco's World Heritage List in 1987. The Ksar, a group of earthen buildings is a traditional pre-Saharan habitat in Ouarzazate province, a striking example of the architecture of southern Morocco


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Ksar Ait-Ben-Haddou’s architectonic details


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View of Ksar Ayt Yahya Watman and its Great Mosque and terrace. Region of Tafilalet

House built in dried adobe in the Pre-Rif finishing


Comb structure of the ceiling after the

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Mosque stone in rural area located in Marrakech Region

Grenier Collectif Agadir Ighir Ifrane – Inoumar. A collective building where the village’s inhabitants store their goods Traditional urban architecture in Morocco is mainly found in the medinas of old towns. The forms and spatial layouts are the result of a combination of influences from the East and sub-Saharan Africa. This cultural crossover has generated a centuries-old urbanism that distributes the surface area between the dwelling, collective facilities and the street layout. The medina is usually surrounded by a town wall that encloses a specific, hierarchical urbanism laid out around an urban nucleus. This nucleus contains religious establishments with their squares, alongside districts devoted to commerce and the craft industry. Then come the residential districts with,


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between them and the town wall, urbanized green spaces. In these quarters, the narrow winding streets converge on larger and more important thoroughfares that lead to the medina’s gateways in the walls. The houses turn their backs onto the street and open up onto their gardens or interior courtyards, ensuring total protection of private family life. The use terraces were traditionally reserved for the women. The riads or traditional houses comprise rooms laid out symmetrically around the courtyard. The façades are made up of colonnades or arches, doors. Inside the rooms, windows flank the doors and alcoves. The service spaces (kitchen, wet areas, circulation) usually occupy the corners. The traditional use of these houses was marked by a degree of nomadism, in accordance with the seasons. The stairs turn around themselves, resting on the masonry walls. As a rule, these constructions do not stand higher than two floors.

4.1.1.2 Classification of the monumental buildings The principal historical and monumental buildings in Morocco can be classified as the following: • • • • • • • • •

mosque minaret palace riad, traditional house medersa foundouk surrounding walls gate of the town triumphal arch, … .

Fez Gate


Ancient urban tissu, Fez medina

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Mrissa Gate, Salé medina (1910)


and nowadays

Rehabilited Foundouk in Meknès medina and Palace in Asila medina

Reconversion of historic houses and palaces


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Sidi Youssef Mosque, Essaouira medina

The Attarin Medersa, Fez medina

4.1.1.3 Local aseismic building techniques: local seismic cultures The Moroccan urban and architectural heritage has been since the beginning of the 1980s subject to a nationally and internationally awareness and increased interest. Owing to this interest for the preservation of the historical monuments and urban fabric, five historical cities are taken into the UNESCO’s list of the world cultural heritage (the medina of Fez in 1981, Marrakech in 1985, Meknes 1996, Tetouan in 1997 and Essaouira in 2001). To reinforce the protection and preservation of these historical centres judicial and political means were set up in the early 20th century and revised several times since then.


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Despite these efforts on both national and international levels, the physical degradation of the historical cities and the unhealthy living conditions, still constitute a threat against the protection and preservation of this valuable cultural heritage. The medinas are currently subject to a continuous degradation caused by overpopulation, promotion of tourism, and by the forced intrusion of modern functions and structures into the historical fabric. The overpopulation in the housing areas has lead to spatial subdivision of the interiors and additional stories carried out according to technical methods totally in discordance with the local building traditions. Badly entertained, the built environment undergoes continuous degradation to the point that the high concentrations of population, the urban equipment and services become unsatisfactory. Most of the historical buildings and monuments are located in active seismic zones which accelerate their vulnerability. These constructions should be preserved over time, especially against earthquakes, which nowadays constitute the most devastating phenomenon. Earthquakes are a complex societal problem, because they have a low annual probability of occurrence, but high probability of causing significant damage to the structures. According to the documentary sources of the historical seismicity and the research carried out in this field (El Mrabet 1991), the built heritage was affected on several occasions by more or less violent earthquakes. Of course, the ancient Communities knew the earthquakes and the various significant aspects of the built environment. They reacted by applying constructive techniques in their habitat and the public and religious buildings as well: a seismic culture existed. Developed countries are nowadays rapidly developing technologies to rehabilitate buildings and are paying more attention to the cultural value of historic buildings. In this context a critical reevaluation of traditional techniques is developing, especially concerning the restoration of monuments. In developing countries, the lost of certain technical expertise is rarely compensated by up-to-date know-how. Even buildings constructed with aseismic techniques are carelessly modified and techniques which are still applicable are gaily abandoned. Regulations, RPS2000 the building code requirements for earthquakes in Morocco, ignore traditional aseismic technologies and thus minimize their values. Structures of architectural heritage and traditional urban housing, by their very nature and history, present a number of challenges in diagnosis and restoration that limit the application of RPS2000. To protect the historical built environment in order to reduce losses, a critical re-evaluation of traditional aseismic technologies can indeed result in a more effective prevention, a more appropriate relief action and less harmful rehabilitation. One consider that in many seismic regions the traditional rules applied to old constructions can often be employed in recent masonry constructions carried out by using stone and earth. It is necessary to reconsider traditional attitudes towards older constructions in the medinas and historic villages situated in seismic regions. Effective protection measures can be implemented by re-evaluating the so-called local seismic cultures (Helly 1995; Karababa 2007), the combination of the knowledge of local aseismic building techniques, and its consequence on behaviour.


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4.1.2 The historic buildings face to earthquakes 4.1.2.1 Morocco’s historic seismicity The geological position of Morocco at the encounter of several interacting tectonic plate is the raison that, historically, Moroccan cities were repeatedly destroyed by several strong earthquakes. Some cities were partially or totally destroyed. It was only at the beginning of the twentieth century that one started to have reliable and scientific information about the earthquakes in Morocco; the first scientific studies of 1904 had shown that Morocco, like the other Mediterranean countries, was exposed to the earthquakes. From 1932, macro seismic investigations were organized by the Cherifien Scientific Institute (become Scientific Institute) thanks to the weather observation network. Indeed, the seismic events in Morocco were seldom reported in the historical and archives documents, as well as in those which deal with the Islamic World history and those related to the specific history of Morocco. The information recorded on the earthquakes in Morocco missed chronological and spatial details. In contrast, the foreign sources which address the history of Morocco have been much more interested in the earthquakes. As a matter of fact, several earthquakes have been mentioned in these sources and were not quoted in the Moroccan historical archives. Certain earthquakes were quite detailed but in general there was confusion of events and an exaggeration of the material and human losses. El Mrabet’s work (2002) largely contributed to the study of this historic seismicity by using the maximum of available sources, Arab, Spanish, Portuguese or French. The richness of these data depended on the intensity of the seism and the proximity of the epicentre to the historical, cultural and political cities, like Fez, Marrakech, Meknes in the centre of Morocco, or to the economic centres like the Atlantic harbours of Tangier in the north and Agadir in the south. From the 9th to the 11th century, the earthquakes were described in a brief way: the writings referred to the destruction of constructions without other precise details. The description became relatively more detailed but the objective remained purely informative. It was at the 17th century that one found the details of the 1624 and 1663 earthquakes reported in a particular mail: the damages which affected the buildings in Fez were mentioned in a detailed way. The extent of the destruction of the 1755 seism, Lisbon earthquake, was mentioned by several sources: the destruction concerned even the palaces and the mosques in Meknes while the damage was less impressive in Fez. In addition, a chronology of the great earthquakes in Morocco since year 881, is presented according to La Grande Encyclopédie du Maroc (1987): -In May 28, 881, an appalling seism affected the two banks of the Detroit. -In December 1 and 30, 1079, a devastating seism destroyed towers, minarets and buildings. Many people perished under the ruins. -In 1276, a violent earthquake caused the destruction of Larache located on the Atlantic coast, causing several deaths. -In September 22, 1522, Fez and the villages of the surrounding areas were completely destroyed; the seism caused also several damages in Tetouan in the north of Morocco. -In January 26, 1531, a violent seism was felt in Morocco but this event is unknown in Moroccan literature. -The earthquake recorded on March 1, 1579 in Mellilia destroyed tens of houses and part of the ramparts of the city. -In May 11, 1624, a catastrophic seism destroyed most of the Moroccan towns of Taza, Fez and Meknes. This earthquake is relatively well documented.


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-In August 5, 1660, the town of Mellilia was affected by a violent seism causing considerable damages. In July 1719, the Moroccan coastal towns recorded a violent seism which has also destroyed part of the town of Marrakech. -In December 27, 1722, a devastating seism caused large damages in the Moroccan coastal towns. -In 1731, another seism destroyed the town of Santa Cruz (Agadir). -In November 1, 1755, the seism which struck Lisbon destroyed the majority of the Moroccan coastal towns from Tangier to Agadir. At this epoch the large cities were especially located inside of the country like Fez, Meknes and Marrakech. One of the well documented destructive tsunamis in the Atlantic Ocean. The Arabic and European archives deal us with so important information concerning the event. About 26 days after Lisbon earthquake, a seism more stronger and violent affected city of Fez after the last prayer of the day: many minarets and mosques were destroyed in different places in the city and about 10 000 persons were killed. -In April 15, 1757, a violent seism destroyed several buildings of Sale town. -In April 12, 1773, a devastating seism almost destroyed all the town of Tangier and several houses in Fez have collapsed. This earthquake was also felt in Sale. -In August 31, 1792, Mellilia was again shaken by a violent earthquake causing the destruction of several buildings. -In February 11, 1848, a disastrous earthquake was felt in Morocco causing of large damages in Mellilia. -In January 21 and 22, 1909, a seism destroyed rural agglomerations located at 5 km from Tetouan and has made hundred victims (between dead and wounded). -In January 4, 1929, an earthquake caused damages in Fez and villages of the surrounding area. -In February 29, 1960, a devastating earthquake of magnitude of 5.7 on Richter scale, destroyed the Agadir causing 12000 deaths; the damages have been estimated at that time up to 290 million dollars. -In February 28, 1969, a violent seism which had his epicentre in the same area as that of 1755 (Lisbon), was felt in almost all Morocco, but it was on the Atlantic Littoral that this seism reached its strongest intensity. -In May 26, 1994, an earthquake of magnitude of 5.7 on Richter scale shook the town of Al Hoceima. -It February 24, 2004, the Al Hoceima province recorded a violent seism of 6.3 on Richter scale causing the collapse of 2539 houses including 2498 in rural areas. The May 26, 1994 (Mw = 5.7 , EMS92 +7) and February 24, 2004 (Mw = 6.3 , EMS92 +8) earthquakes that affected the Al Hoceima region of northern Morocco are the two strongest events recorded in this region. Ten months after Al Hoceima earthquake, there was an important but largely ignored event characterized by a vigorous seismic series with a magnitude from 4.3 to 5.3, located about 100


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kms SE from Al Hoceima. However, its proximity to large population centre (Nador city, 109 000 inhabitants) was important. A maximum intensity of EMS 7 was observed in Douria village, with widespread damage of grade 3 to vulnerable buildings (Source: Patrick Murphy Corella). CNRST’s recent studies (Centre National de Recherche Scientifique et Technique, Morocco) have given two principal results: -70% risk for the occurrence of a Magnitude 7.0 earthquake within a period of 100 years for some regions; -more than 20% of total population live in seismically active geographical areas where moderate earthquake hazards to major damaging earthquake can occur at least once in a lifetime. What is interesting in this chronology of the major earthquakes in Morocco, it is the frequency of the earthquakes which struck the town of Fez (1046, 1079, 1408, 1522, 1623, 1624, 1708, 1755, 1773, 1776, 1867), so much that its inhabitants believed that the ground of their city often moved because it was hollow and full of subterranean water.

4.1.2.2 The seismic design code for buildings Morocco is located at the extreme northwest tip of Africa, in a region that constitutes a plate boundary between the African and Eurasian plates. In fact, starting late Cretaceous, early Cenozoic times, Africa has entered in a phase of nearly N-S compression with Eurasia. The current state of stress being in a NNW-SSE direction. The recent geodynamic evolution of northern of Morocco is thus directly linked to the interaction between these two plates. At a regional level, Morocco is under the influence of the Azores-Gibraltar line of seismicity, which is a major complex transform fault that connects the Mid-Atlantic ridge to the Gibraltar area, and that produced very large earthquakes in the past. To the north, the Alboran sea which has a 17 km thick continental crust (Docherty and Banda, 1995) and the Spanish Betic mountains, which are the European symmetric counterparts of the Rif mountains. The convergence between the African and Eurasian plates produces N-S to NNW-SSE compressive stresses. In this region, these stresses acting on surface faults of NE-SW direction cause an activation of these faults along which they generate mainly strike-slip movements, and produce reverse movements along nearly E-W oriented faults; that is thrust nappes of the Rif and Betics. Figure 1 shows the seismicity recorded in Morocco and its neighboring regions in the period 1990-2007. To the north of Morocco, a line of strong seismicity extends from the Gibraltar strait, all the way to the Atlantic Ocean. This line of seismicity reflects the interractions between the colliding African and Eurasian plates at the boundary that separates them. Within continental Morocco, Figure 1 indicates strongly that the seismic activity, is mostly concentrated along the Rif and the Atlas mountain belts. The Rif intermountain belt, in the northernmost Morocco, being the most active. This activity can be to thrust nappes that form inverse faults that are near-vertical at the surface, but get less steep with depth and flatten out to join a near-horizontal detachment surface. The thrust nappes are bounded by strike-slip faults that are capable of producing strong earthquakes such as the Al Hoceima 1994 and 2004 earthquakes that caused sever damages in the Al Hoceima region. The Al Hoceima 2004 Damage based selection of techniques

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earthquake caused the death of more than 620 people and the important number of destroyed houses showed that the building stock in Morocco is very vulnerable to earthquakes. Although the seismicity is less frequent (Figure 1) in the Atlas mountains, the important height of these structures along with the ongoing seismic activity indicate that these mountain belts are capable of producing large destructive earthquakes such as the Agadir 1960 eathquake. Indeed, this event caused a 15 000 death and 3650 collapsed Buildings. Morocco is exposed to a number of natural hazards such as earthquakes, but the regulatory framework for risk management has not been yet fully established. Recent even (the earthquake of February 2004, Al Hoceima in the northern region) demonstrated the lack of preparedness of the country to cope with natural disasters. This earthquake was however the occasion for strengthening the efforts to apply the national building code requirements for earthquakes (RPS2000), to create a new approach to civil protection and the recent creation of the National Committee of Earthquake Engineering. The first seismic building code at a national level was elaborated only in the year 2000 and it is still under review and amendment, but the legislation of its enforcement became underway in the year 2002. The different structures concerned by the Code include RC frame and wall bearing structures. The Code is used for new constructions and great modifications of existing buildings. However, it is not applied to bridges, dams, industrial buildings such as nuclear and electric units, and buildings realized by materials or systems not stipulated by the standards. After 8 years of existence, the RPS 2000 does not seem to achieve all the goals initially discounted at the time of its elaboration due to a mentality problem, a professional engagement problem, but also due to some difficulties of application and comprehension. Some of architects and Engineering Offices were not prepared with the application of this law and the computational tools were not standardized. Fortunately, this Code is improving and is presently under revision. The new main seismic zones and the corresponding acceleration coefficients with a 10% exceedance probability in 50 years are shown in Figure 2, including five, instead of three zones in the first version, with accelerations that vary between 4%g and 18%g.


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Figure 1: Morocco’s seismicity map (1900 – 2007) (Source: CNRST, Morocco)


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Figure 2: Seismic zones (5 zones instead of 3 zones in the Codes’s first version) (Source: Revised RPS2000, 2008)

4.1.2.3 The built heritage face to earthquakes The medina like Fez is regarded as a good example of the experiment of the old frame face to the earthquakes. In addition to the compact architecture of the old frame, the knowledge of the local construction practices is fundamental and should guide the choice for successive restoration and rehabilitation operations. The principal building materials used in the construction include the hearth blocks, as well as plaster, wood, and stone. Traditional ceramic tiles, zelij, or cedar woodwork are the common finishing materials. Indeed, one of the constructive typologies of the structure load-bearing wall is the masonry carried out with earth bricks, and bound by a loam mortar or lime, between which are intercalated wood elements of cedar. This provision of two materials, one rigid and the other flexible device, allows an absorption of the seismic horizontal loads. The renovation and restoration work on the other hand has been done with mostly traditional materials and methods of construction. Local masons and craftsmen do the majority of the work.


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4.1.3 Local construction practices 4.1.3.1 Introduction Some anomalies are apparent in the old frame and they correspond to a change in constructive methods. But these are normal because they express the answer of the Community to new solicitations, aiming at restoring, rehabilitating or solving structure stability problem. The frame thus modified will be naturally exploited and the solution that has been found will be re-used if it proves to be the good one. The anomaly introduced into the frame will then change step by step, to a voluntary anomaly and classified as a local constructive practice and as an answer to any event, an earthquake for example (Ferrigni 1990).

Example of anomalies: Sale medina rampart A sampling of these local construction practices apparent in the medinas have been presented (El Harrouni 2005). The recovery of these traditional methods could then be developed as being soft “para seismic” measurements (Laurenti 2002) applicable to the old frame for the protection and conservation of the historical architectural heritage.

4.1.3.2 Buttresses When a frontage wall or a great wall presents a cant, the response of the Community to this problem is almost always the same one: the use of a buttress, a mass of masonry built against a wall to strengthen it. This system is a consolidating element to the existing structure and it is generally added to an older masonry building. Sometimes, the buttress is carried out at the same time as the building construction, a voluntary and premeditated act to reinforce this construction, generally at the corners of the structure. In the areas subjected to the seismic risk, the buttress frequently accompanies the stone frame and becomes an essential element to achieve the building stability. Sometimes, the buttresses were used both as utilitarian and decorative forms. They can be also used as staircase ensuring the access to the dwelling, built to play the role of the confortement, a judicious way to associate reinforcement technique with comfort. The unreinforced masonry structures have very low stress level and their stability, not strength, governs the safety, but the geometry changes may threaten stability of the structure. For high


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vaulted buildings, the arch will collapse and the buttress will remain standing in most cases. A masonry buttress will fracture at collapse, reducing its load capacity.

Meknes medina rampart with buttresses

Use of buttress in Chechaouen medina

4.1.3.3 The basement and the vertical reinforcing chains The basement has an importance in height to ensure a stable base on which rises a building, a historic monument for example. The vertical reinforcing chain made out of cut stone, is another means of reinforcement and consolidation of the building corners, which is generally used in colonial architecture and fortified architecture. The reinforced basement and the rebuilt angle chaining using building materials different from the original masonry, are very apparent actions on the frame and could belong to the indicators making it possible to suppose damages caused by a seism.

Al Kamra Tower in Asila medina

Rampar and tower in Salé mdina

4.1.3.4 Contrasting arches and Sabats The medina urban structure is very affected by the constraints of the site and is organized in an irregular network of narrow streets rarely rectilinear, which surround all sides the blocks, separate them from each other allowing them a dynamic behaviour during the earthquakes. These separating spaces play the role of an empty joint of separation. This urban morphology and building construction with narrow streets are probably a solution to reduce seismic damage and prevent the houses from collapsing.


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The houses are semi-detached, overlapping and leaning against each other forming a compact unit. Some streets are covered by galleries on top of which the houses extend and thus creating roofed passageways called ‘the sabats’. This extension can also be done in height thus from the starting of the sabats, which are extensions of the houses on the top of the public space, which cover it and form passageway (Abdessemed-Foufa 2005). Those are elements of cuts in the linear continuity of the frontages, realized either in vaults built out of stones or bricks, or flat with wooden logs incorporated. Those are elements of reinforcement which play a determining role in the bracing of the blocks between themselves. In addition, the medina urban framework is characterised by a certain number of arches built out of stone or bricks, called “confortement” arches or contrasting arches whose relative flexibility and elasticity allow the transmission of the of the horizontal stresses and their transfer to the ground. The buildings are not considered any more as isolated elements but as a compact dynamic block. This bracing is always present in the narrow streets of the medina and allowed the constructions not to collapse.

Contrasting arches in the Fez medina

Contrasting arches in the Azzemour medina


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Roofed passageways or ‘Sabats’ in Chechaouen and Rabat medinas

4.1.3.5 Discharging arches and framed openings A discharging arch or relieving arch is an arch over a door, window, or other opening, designed to distribute the pressure of the wall above. An opening in a frontage constitutes a vulnerable point in the event of deformation of the frame. The cracks of the front walls are found in the contours of the openings where the stresses are most significant and in particular close the reentrant angles. The earthquake-resistant design codes recommend, for masonry structures, rigid reinforced concrete, steel or wood framings of the openings and, in principle, must be connected to the links of the walls. The wooden framings must be effectively connected to the masonry. The openings in the medina, doors and windows, are framed by wood and well connected to masonry. Cut stone arcs are also located at the top of these openings.

Discharging arch in Sale medina and Rabat extramurus

4.1.3.6 Arcades and wooden tie beam systems As mentioned above, the bracing is one of the most significant aspects of the earthquakeresistant design. A basic principle is that of the monolithism, according to which the various parts of the structure must be suitably connected between themselves to avoid the dissociation of their elements under earthquake loads. This technique results essentially by the bracing arc which binds the two different masonry structures to the arcades and which become bind together. They are consolidated by a wooden beam system which connects the frontages of the


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galleries to those of the load-bearing walls to ensure the stability of the walls with those of interior and avoiding their opening and collapse. Their distribution is rather regular and is particularly observed in the traditional courtyard houses. The use of this linking system shows again the manner of the earthquake loads resistance.

Use of bracing and wooden tie in Rabat and Meknes medinas

4.1.4 Historical buildings protection strategy The approach of combining conservation requirements with safety, within the restoration of historical city centres was often seen, and still not an obvious requirement for policy makers. Therefore, it is necessary to develop “Codes of practice” that contain all available information on local seismic activity, original construction techniques and precarious situations, suggesting methods of validation of the proposed structural modifications. This should help those responsible for planning the actual site works to select adequate and efficient techniques, which respect the local culture and limit future damage (Lourenço 2007). In order to preserve and protect historical buildings and monuments from the potential impacts of earthquakes, the first phase is to understand how ancient Communities have built their cities. Some protective arrangements listed above have been put in evidence following site investigations in Moroccan medinas, including some historical monuments and traditional courtyard houses. These constructive techniques have certainly played an important role in the resistance to earthquake loads. The following propositions constitute the starting point for the development of an efficient and cost effective protection strategic plan (Benouar & Abdessemed-Foufa 2002) for historical buildings: -Politically, accept that historical buildings are not only objects to preserve but they also constitute a national and regional scientific resource. -Promote these traditional seismic protective measures rediscovered in historical sites. -Contribute to the understanding of these local construction practices that have protected the historical buildings, monuments and sites. -Analysis and study of the construction practices evolution during the last centuries (typology, morphology). Damage based selection of techniques

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-Characterisation of the seismic source parameters related to the area under consideration. -Integration of these techniques into national building codes. -Revival of old professions capable of dealing with historical buildings. -Study the effects of an expected seismic event (i.e., a scenario event) on the site containing a relevant historical structure, using the scenario to characterise the behaviour of different structural typologies, including local seismic cultural elements. -Identify the main historical buildings, monuments and sites at risk, in order to take reinforcement actions of the relevant structure by implementing these traditional techniques. -Transmit the traditional seismic preventive techniques to decision makers and end users. -Provide end users (engineers, architects, decision makers, politicians, civil protection, etc.) effective and comprehensible descriptions of the procedure.


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4.1.5 Dwellings stock seismic vulnerability assessment in urban areas 4.1.5.1 Introduction As we said before, Morocco has suffered the effects of a number of destructive earthquakes in the past century, some of which were quite severe, such as the earthquakes of 1960 in Agadir and the latest one at Al Hoceima in the year 2004. The 1960 Agadir earthquake, one of the most deadliest in Morocco through at least the last two centuries, caused substantial loss of life and property. According to governmental sources, 12 000 people lost their lives, and another 24 000 suffered injuries of various degrees. 3650 houses were destroyed while 250 houses were damaged to varying degrees. In the 2004 Al Hoceima earthquake, 628 people lost their lives and tree thousand dwellings collapsed or got heavily damaged. Reasons for this high damage degree can be attributed to several causes: poor quality residential construction and development, excessive urbanization, ineffective control/supervision of design and construction, regulations with limited enforcement mechanisms. We try to present some assessment results of the dwellings stock vulnerability in urban zones under different seismic intensities. For this purpose we have used the results of a survey on the dwellings stock in Morocco, which was implemented by the Housing Department and launched in the year 2000. It was a nation-wide investigation on dwellings that provides such basic information as type of structure (masonry, RC, other), period of construction, number of stories, and state of efficiency. In Morocco, the urban housing constitutes 55% of the total dwellings stock, while the rural buildings present 45% of this building stock.

4.1.5.2 Common Urban building types Six main types of housing in urban areas have been identified: (i) villas (3.1%), (ii) buildings with several storeys and apartments (14.5%), (iii) Moroccan traditional houses (7.3%), (iv) Moroccan modern houses (65.4%) which are usually single family independent houses, (v) structureless houses (8.6%) which are illegal type houses for which no construction norms were applied and are thus, very vulnerable seismically, and (vi) rural settlements within urban areas (1.1%).

4.1.5.3 Building materials and construction systems The most building materials used in the constructions and the common types of structures are: 1. The Earth Architecture using mud brick (adobe), rammed earth (pisé) and compressed earth block. 2. Masonry: Fired bricks, concrete blocks (hollow or solid) performed using cement mortar and natural stone are used for the construction of masonry walls. In all cases the quality of masonry units should comply with the local national requirements with regard to materials and manufacture, dimensions and tolerances, mechanical strength, water absorption, frost resistance, soluble salts content,… . 3. Reinforced concrete (RC): reinforced concrete frames with concrete beam-hollow block slabs and masonry infill walls.


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The confined masonry, a construction system where masonry structural walls are surrounded on all four sides with reinforced concrete, is also used. In order to ensure structural integrity, vertical confining elements are located at all corners and recesses of the building, and at all joints and wall intersections. The extensive loss of life and property caused by earthquakes may be reduced to a considerable degree by the adoption and implementation of improved design, sitting and construction procedures practicable within the context of the cultural and socio-economic constraints prevailing in the given regions. The assessment survey’s key findings regarding these types of construction materials are as follows: - 83 % of Morocco’s dwellings stock were found to incorporate the RC as vertical structure with brick infill; - 96% of the constructions use RC in the floor/roof system; - the concrete is present as well in the adobe/pisé construction, but at very low percentages, namely 7% in the vertical structure and only 6% in the roofs; - the use of other materials such as the adobe, the stones or the branches of reeds at the level of the walls remain little used. These are sometimes associated with the reinforced concrete which gradually prevails as the techniques of construction evolves; - other materials such as reeds, clay, corrugated zinc sheets, frame of wood are occasionally encountered in the roofs but of very limited use;

4.1.5.4 Vulnerability assessment Several methods are used for the assessment of buildings vulnerability. We adopt a semiempirical method for the computation of the buildings vulnerability index and fragility curves for the different vulnerability classes. These fragility curves have been used to simulate the consequences of a seismic intensity IX on the different vulnerability classes. The following Table summarizes the vulnerability classes for these different types of constructions both in urban and rural areas. For rural settlements, the use of locally available natural resources as building materials is common. These include raw bricks or adobe, dry stones or stones with earthen mortar, earthen pisé, tree branches or reeds with or without zinc or coating soil material. The class of vulnerability of the rural house for all these types is considered to be A. Three different types of vulnerability for class A (A1, A2, A3) were introduced, based on structural typologies which present different vulnerability exposures.


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Table : Vulnerability classes versus structures per type of construction Construction Type Structurele -Villa ss -Moroccan constructio modern house Buildings with Building ns less than 7 higher than 6 Structure -Moroccan & Rural stories stories traditional settlements house Brick filling with Vulnerability class R.C. structure C

Vulnerability class

Vulnerability class

-----

C D

Stone filling Vulnerability class with cement mortar B Dry stone or Vulnerability class stone with earth mortar A3 filling

Vulnerability class -----

-----

-----

Vulnerability class

-----

A3 Vulnerability class

B -----

Adobe -----

-----

A2 Wood branches, zinc, reed or pisé filling,

------

------

------

Vulnerability class A1

a) Mean Damage Grade µD and Vulnerability Curves: Vulnerability is a function of earthquake intensity I and of the vulnerability index which are related by a formula that links µD to I and VI: D

2.5 1 tanh

I 6.25 VI 13.1 2.3

where: µD is the mean damage grade; I is the macroseismic intensity and VI is the vulnerability index.


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Damage Assessment µD : The following Table shows values of µD as a function of the seismic intensity I for each vulnerability class: Table : Mean damage grade µD as a function of I for each vulnerability class Intensity I

µD (A1)

µD (A2)

µD (A3)

µD (B)

µD (C)

µD (D)

5

0.5735

0.5206

0.4721

0.1611

0.1055

0.0447

6

1.1807

1.0855

0.9960

0.3680

0.2446

0.1056

7

2.1224

1.9909

1.8622

0.7968

0.5345

0.2431

8

3.1882

3.0609

2.9305

1.5571

1.1324

0.5461

9

3.9152

3.9510

3.8580

2.5951

2.0563

1.1321

10

4.5462

4.4993

4.4481

3.6012

3.1252

2.049

11

4.7992

4.7772

4.7529

4.3000

3.99

3.115

12

4.9139

4.9041

4.8934

4.6806

4.5232

3.8914

Figure 4 shows values of the mean damage grade µD for each vulnerability class, as a function of the seismic intensity I.

µD mean damage grade

5

4

3

A1 A2 A3 B C D

2

1

0 5

6

7

8

9

10

11

12

sismic intensity

Figure 4: Vulnerability Curves for the different building classes (A, B, C et D) in Morocco.


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Vulnerability index VI : The estimation of the vulnerability index VI of a construction is a function of its type of structure (VI*) and of the vulnerability modifier scores (Vm) which depend on the state of the construction and on its construction site. The following Table gives the vulnerability index for the different buildings vulnerability classes Table : Estimation of the vulnerability index VI vulnerability indices

VImin

V-I

V+I

VI*

VImax

Vm

VI = VI* + ΔV m

Wood branches, Zinc (A1)

0.62

0.83

0.9

0.96

1.02

+0.02

0.92

Adobe, pisé (A2)

0.62

0.83

0.86 0.96

1.02

+0.04

0.90

0.62

0.83

0.82

0.96

1.02

+0.06

0.88

0.46

0.50

0.51

0.83

0.86

+0.16

0.67

Reinforced Concrete (C)

0.30

0.34 0. 43 0.83

1.02

+0.16

0.59

Buildings (N° of stories ≥ 6)

0.14

0.18

0.86

+0.05

0.43

Dry stone or earth

mortar

(A3) Stone with cement mortar (B1, B2)

0.38 0.83

(D)

VImin & VImax are the minimal and maximal values for the vulnerability index. [V-I ; V+I] is the interval where the vulnerability index takes the most probable values (they’re usually obtained for χ = 0.5). b) Fragility Curves: Damage Distribution The Damage Probability Matrices (DPMs) are modelled using the beta distribution as follows: r 1

PDF : p x

where: a=0

b=6

t=8


r

r

t x -a b-x t 1 t r b a

t 0.007

3 D

0.052

2 D

t r 1

0.2875

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a

D

x Dk)

P(D > Dk)

80

60

40

60

40

20

20

0

0 0

2

4

0

6

2

4

6

DAMAGE GRADE

DAMAGE GRADE

Damage state for class B buildings.

Damage state for class A buildings.

80

100

80

60

P(D > Dk)

P(D > Dk)

60

40

40

20

20

0

0 0

2

4

6

0

Damage states for class C buildings.

2

4

6

DAMAGE GRADE

DAMAGE GRADE

Damage states for class D buildings.

Figure : Damage states for a seismic intensity IX on all four classes of buildings.


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Figure : Soft storey damage to this RC building in Al Hoceima region. (grade 3 vulnerability C)

Figure: On the right: building with ground floor collapse (grade 5 vulnerability C) On the left: both ground and first floors failed in this building (grade 5 vulnerability C)

Figure: Damaged column and soft storey damage (grade 4 vulnerability C) Damage based selection of techniques

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Figure: Shear damage to the hollow brick wall with RC frame (grade 2 vulnerability C)

Figure: Advanced corner failure of traditional masonry. Rural area in Al Hoceima region (grade 4 vulnerability A)


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4.1.6 Componennet typologies and damage mechanisms 4.1.6.1 Masonry construction in seismic areas

(a) (b) (a) Section through a masonry wall with fieldstone arranged in a weak mortar (b) Section through an adobe brick wall with a weak diaphragm roof (Patrick Murphy Corella, 2004) The poor mortar fill of traditional masonry fieldstone construction often results in a behaviour approaching that of two independent walls. A common observed damage is the loss of one of the two wall components, as modelled above and as shown through the loss of the external wall of the masonry load bearing wall in a mosque in rural area. Another type of damage in masonry construction is the shear damage in load bearing walls including the x-cracks. The picture shows the shear damage to the piers on the ground floor of an unreinforced brick and stone masonry building. The third damage in masonry construction is the corner failure: The cyclic reversal of strain in two perpendicular walls meeting at a corner causes brittle failure in unreinforced masonry construction resulting in this widespread earthquake damage.


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Traditional masonry wall damage: Failure of external skin of load bearing wall

Shear damage formation

Corner damage

4.1.6.2 Earthen wall behaviour under seismic loading Damage based selection of techniques

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The failure modes of the earthen walls subjected to the vertical and horizontal loads are of three types: (a) Failure by slip: The wall undergoes a relative displacement along a plan of low shear strength such as the joint of horizontal mortar (adobe), the construction joint of built (cob), … (b) Failure under bending: The wall behaves like a cantilever beam subjected to bending moment and axial force. (c) Shear damage characterized by the formation of the diagonal cracks.

Under the horizontal loading, the wall undergoes vertical and horizontal inflections:

Lateral inflexion of the earthen wall

Computations model of the earthen wall vertical inflexion

4.1.7 Building typologies and damage mechanisms 4.1.7.1 Towers, Minarets


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Agadir Kasbah destroyed by Agadir Earthquake, 1960 In 1572 a stronghold, the Kasbah, was built on the top of the hill overlooking the bay of Agadir, which means in Berber "wall, masoned wall enclosing a town, fortress, town". Agadir became prosperous for two centuries. But in 1731, the town was completely destroyed by an earthquake and in 1960, the Agadir earthquake destroyed the ancient Kasbah. The mosque minarets were subjected to strong shakng of Al Hoceima Earthquake in 2004. A simple model for non-structural damage to the mosque lantern is shown the following pictures. All mosque minarets are built to similar geometric specifications; a RC frame with no diaphragm action save for the spiral stairs. Lantern is a non-structural element on the roof. In some of these mosques, the lantern collapse, the shear damage to the tower base and the plastic hinging at base of tower have been observed.

Failure model: lantern collapse and plastic hinging

General view of the mosque complex Regarding this mosque complex, vulnerability C is assigned to the tower only; the prayer hall is vulnerability A and shows damage of grade 3.


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Twisting of the lantern

Lantern collapse

Shear damage to base of tower


Lantern collapse

Damage to the diaphanous tower

REFERENCES Abdessemed-Foufa, A., Contribution for a Catalogue of Earthquake-Resistant Traditional Techniques in Northern Africa: The case of the Casbah of Algiers (Algeria). European Earthquake Engineering Journal 2(5): 23-39, 2005. Damage based selection of techniques

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Benouar, D. & Abdessemed-Foufa, A., Reducing the Natural and Environment Disasters on Historical and Archaeological Monuments and Sites. Actes des Rencontres du Groupe APS. 2002 Corella P. M., “Al Hoceima Earthquake 24 02 2004”, Field report, Patrick Murphy Corella Architect, June 2004 EL Hammoumi, A. Iben Brahim, A. Birouk, E. A. Toto, A. EL Mouraouah, M. Kerroum, K. Gueraoui, M. Kasmi, “Assessment of Seismic Vulnerability of Urban Buildings in Morocco”, Int. Review of Mechanical Engineering, Praise Worthy Prize S.r.l., Vol. 3, n. 1, 2009 EL Hammoumi A., Iben Brahim A., Toto E. A., Hafid M., Kerroum M., EL Mouraouah A., Kasmi A., Birouk A., EL Harrouni K., “Seismic Protection of Ancient Medinas in Morocco. A Study Case of Foundouk Bouâlam”, International Review of Mechanical Engineering, Praise Worthy Prize S.r.l.,Vol. 3, n. 3, 2009 EL Harrouni K., “Protection of Historical Buildings by Re-discovering and Re-evaluating Local Seismic Cultures”, in PROHITECH 2009, Proceedings, International Conference “Protection of Historical Buildings by Reversible Mixed Technologies”, Rome – 21st to 24th June 2009 EL Hammoumi A., Gueraoui K., Cherraja M., Kerroum M., Iben Brahim A., EL Mouraouah A., Kasmi M., Birouk A., Toto E. A., Hafid M., EL Harrouni K. “Seismic Vulnerability Analysis and Computer Simulations and Modelling; Case Histories”, in PROHITECH 2009, Proceedings, International Conference “Protection of Historical Buildings by Reversible Mixed Technologies”, Rome – 21st to 24th June 2009 El Harrouni, K., “Reducing Vulnerability of the Cultural Heritage by Rediscovering and Reevaluating Local Seismic Cultures”, WCDE, Cultural Heritage Risk Management, Proceedings Kyoto & Kobe, 15-22 January 2005:177-180. Kyoto: Rits-DMUCH, 2005 El Mrabet, T., Les Grands Tremblements de Terre dans la Région Maghrébine et leurs Effets sur l’Homme et l’Environnement. Thèse d’Etat. Rabat : FLSH, Université Mohamed V, 2002 El Mrabet, T., La Sismicité Historique du Maroc. Thèse de 3ème cycle. Rabat: FLSH, Université Mohamed V, 1991 Ferrigni, F., San-Lorenzello, à la Recherche des Anomalies qui Protègent. Réseau PACT, CUEBS de Ravello, 1990 Helly, B., Local seismic cultures: a European research program for the protection of traditional housing stock. Annali di Geofisica Vol. XXXVIII (5-6): 791-794, 1995 Karababa F., Local Seismic Construction Practices as a Means to Vulnerability Reduction and Sustainable Development. A Case Study in Lefkada Island, Greece, PhD Dissertation, University of Cambridge, 2007 La Grande Encyclopédie du Maroc, M. Kenbib (ed.), Histoire. Rabat, Bergamo: GEM, Gruppo Walk Over, 1986 Laurenti, A., Regard sur la Sismicité Historique de la Commune de Peille dans les AlpesMaritimes. Actes des Rencontres du Groupe APS, 2002 Damage based selection of techniques

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Lourenço, P.B., Cultural Heritage Buildings: Vulnerability to Earthquakes and Principles for Structural Conservation. Jurnal Alam Bina, Jilid 9(3): 65-77, 2007 Ministère de l'Habitat, de l'Urbanisme et de l'Aménagement de l'Espace, Unniversité Mohammed V-Agdal, Premier Draft du RPS2000 Révisé Version 2008, Première Rencontre Scientifique, Rabat, Février 2008 Royaume du Maroc, Ministère Délégué Chargé de l’Habitat et de l’Urbanisme, Règlement de Construction Parasismique (RPS 2000) (Applicable aux Bâtiments), Juillet 2001, Direction Technique de l’Habitat, Edition 2006


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5 PARTNER N° 11 - CDCU 5.1

ARCHITECTURE AND CONSTRUCTIONS IN EGYPT: BUILDING MATERIALS AND TECHNIQUES

5.1.1 Introduction Earthquakes are among the natural hazards that can result in the deterioration of buildings to an unlimited extent based on some parameters, including those related to the quake itself, e.g. its magnitude and duration, and others related to the building itself and its bedrock, e.g. construction type; construction height; type of subsoil; and state of building ‘‘damage category’’ before the quake. Limestone and sandstone were the main building stones of ancient Egypt. From Early Dynastic times onward, limestone was the material of choice for pyramids, mastaba tombs, and temples within the limestone region. From the late Middle Kingdom onward, sandstone was used for all temples within the sandstone region as well as many of those in the southern part of the limestone region. Marble was used from Greek Roman period until Islamic period as an ornamental stone. Mud Brick was used as the main building material in some of prehistoric, old kingdom tombs and monastery during the Byzantine period. Red Brick was used in Egypt from the Greek Roman period on ward.

5.1.2 Building Materials and Techniques 5.1.2.1 Ornamental Stones The principal applications of the various stones and their periods of use are as follows. Exterior veneer on pyramids: Old Kingdom – granite, and granodiorite. Pyramid capstones: Old and Middle Kingdoms – granodiorite, and possibly basalt. Linings of burial chambers and passages in pyramids and mastaba tombs: Early Dynastic period through Middle Kingdom – granite, granodiorite, and siliceous sandstone. Door lintels, jambs and thresholds of temples: Early Dynastic through Roman periods – granite, granodiorite, and siliceous sandstone. Temple pavements: Old Kingdom – basalt, and travertine. (6) Temple columns: Old and Middle Kingdoms – granite. Interior wall veneer, pavement and columns for temples and other buildings: Roman period – andesite-dacite porphyry, granite, granodiorite, metaconglomerate, metagabbro, metagraywacke, pegmatitic diorite, quartz diorite, rhyolite porphyry, tonalite gneiss, and trachyandesite porphyry. Basins: Roman period – granite, andesite-dacite porphyry, and tonalite gneiss. Barque shrines: Middle and New Kingdoms – granite, siliceous sandstone, and travertine. Obelisks: New Kingdom and Roman period – granite; and New Kingdom only – metagraywacke, and siliceous sandstone. Offering tables: Old Kingdom through Roman period – granite, granodiorite, metagraywacke, siliceous sandstone, and travertine. Unreinforced masonry structures are the most vulnerable during an earthquake. Normally they are designed for vertical loads and since masonry has adequate compressive strength, the structures behave well as long as the loads are vertical. When such a masonry structure is subjected to lateral inertial loads during an earthquake, the walls develop shear and flexural stresses. The strength of masonry under these conditions often depends on the bond between brick and mortar (or stone and mortar), which is quite poor. This bond is also often very poor when lime mortars or Damage based selection of techniques

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mud mortars are used. A masonry wall can also undergo in-plane shear stresses if the inertial forces are in the plane of the wall. Shear failure in the form of diagonal cracks is observed due to this. However, catastrophic collapses take place when the wall experiences out-of-plane flexure. This can bring down a roof and cause more damage. Masonry buildings with light roofs such as tiled roofs are more vulnerable to out-of-plane vibrations since the top edge can undergo large It is always useful to investigate the behavior of masonry buildings after an earthquake, so as to identify any inadequacies in earthquake resistant design. Studying types of masonry construction, their performance and failure patterns helps in improving the design and detailing aspects. Cracks are an indigenous, undesirable feature in many archaeological buildings. Some cracks are a result of wear and tear, while others are related to earthquakes or construction or design defects. Expansion and contraction of soils, consolidation of soil, vibration, wind, overloading and impact are some causes of cracks in buildings. Insurance coverage for repair of cracks may be extended or denied depending on determination of the cause of the crack. Masonry and timber are the most common building materials that can be found widely used in Egyptian buildings. Naturally, innumerable variations of these materials, techniques and applications occurred during the course of time. The influencing factors were mainly the local culture and wealth (buildings in Lower Egypt are more rich than those of Upper Egypt), the knowledge of materials and tools, the availability of material and architectural reasons. In some buildings, traditional building materials were almost exclusively local materials, usually used without much processing or with a minor improvement using elementary tools. The external walls of the most ancient Coptic buildings are made of irregular masonry. The stones are of variable size, sometimes with stone slabs used as an external ornament. Small stones and brick fragments are used to fill larger voids, with joints made of clay or clay–lime mortar. Walls are, usually, rendered with lime or clay mortar and painted with lime wash, creating flat and white facades suitable for applying colored scenes. Timber (or, rarely, stone) lintels strengthen window and door openings. The timber beams that sustain the floors and roofs are supported directly in cavities in the external masonry walls (which become later an aperture for rain water to the inside). The internal walls can be built with different techniques. Then, the surface is plastered and painted with lime wash. Properties of masonry constituents Building materials are characterized by a number of properties, which differentiate among the similar types, and differ in value from one material to another. It is the best measure for current status of building materials, and the base on which assessment study, of the historical building under conservation and restoration, depends. In the previous part, we’ve discussed the different Islamic periods in Egypt, their architectural styles and building materials. These building materials were mainly masonry, whether brick, stone or both. Also different mortars were used like gypsum and lime mortars. Building materials are classified into three main groups: 1. Main Building Materials: They comprise most of the structural elements in the buildings (i.e.: foundation, loadbearing walls, columns, roof system, ..etc.). The main building material of historical Islamic structures may be either brick-masonry or stone-masonry units. 2. Auxiliary Building Materials: They exist in building construction in considerably small amounts but the entire work can not be achieved without. The major example is mortar in joints and rubble infill. 3. Ornamentation and decorative materials: They are used to cover the interior and exterior surfaces of buildings, in order to add a touch of art and beauty to the living from inside and viewing from outside. These materials are such as: plaster, rendering materials, stucco etc. They vary widely according to many aspects and considerations.


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In this part we will discuss different main building materials used in historical buildings, their manufacturing or preparation to be ready for use in construction works, and the different properties of each material. Then we will discuss the masonry buildings: their construction systems and their behaviors. In fact, the main aim is to give sufficient information about masonry materials and building systems of historical Islamic structures, which may be used in very limited scale nowadays. General definitions for masonry works Masonry: Is a general name for a construction material composed mainly of stone or brick units and bound together by mortar. It is commonly given to stonework and construction with stone, although scientifically this expression can be used with both brickwork and stonework. Mason: A person who carries out the construction works with masonry units. Masonry unit: It is the major constituent in masonry works, it can be classified as follow: • By material type: it can be either stone or brick. • By dimension and shaping: it can be one of the following: a) Brick b) Block c) Random rubble According to Egyptian Code Of Practice For Masonry Works (E.C.P.M), part III, it classifies the masonry units as follows: Brick: Is a masonry unit which dimensions do not exceed one of these values: (30 cm) in length, (20 cm) in width and (20 cm) in height. Block: Is a masonry unit which when used in its normal aspects exceeds the length, width or height specified for bricks. It can be of stone or brick material. .... For both bricks and blocks, the surface of all its faces (sides) must be finished to be completely flat and smooth as possible. Random Rubble: Is a stone used in masonry buildings as it was cut. All its sides are not flat, but irregular and random, and sometimes it can be slightly dressed. Pier (Buttress) It is a vertical structural member in the building, constructed with masonry units that interlock with other units of masonry walls which pier supports. It may project from a wall, located at building corners or at the intersection of cross-walls. Its length should not exceed four times its width in cross-section. It may be either engaged to the wall that it supports or isolated which it is not connected to any wall. Masonry wall It is usually a vertical structural member in the masonry building which is constructed of certain masonry units. Its length exceeds four times its width. It may belong one of the following types: Non-Bearing (Non-Structural) Masonry Wall: It does not carry any vertical load apart from its own weight, although it may be exposed to lateral loads. Loadbearing (Structural) Masonry Wall: It is a wall primarily designed and aimed to carry vertical imposed loads in addition to its own weight, and it may be exposed to lateral load, Damage based selection of techniques

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which is not the main aim of its roll, as walls which mainly constructed to support lateral loads do not follow this wall type, (always are called ‘retaining walls’ ). Panel Wall: It is an internal partition (non-bearing wall) inside buildings which is carried by floor slabs. Curtain Wall: It is an external non-bearing wall, which is constructed on facades and carried on beams and other structural elements of the building. Parapet: It is a vertical short wall (with limited height), that is built to protect people from falling down from upper floors. Masonry Works It is a general expression which describes the assemblage of masonry units bound together with mortar, which may be of brick-masonry or stonemasonry. These works can be a wall, pier, buttress, or any other system. (I) Brick Masonry Units Historical Islamic buildings always include brick-masonry works, as they were widely used during all Islamic periods in Egypt and other Islamic countries, with a variety of types and shapes. Some buildings are totally constructed of bricks, such as the Tulunid Mosque in Cairo, beside many other examples. This section will discuss all major types of historical bricks that were produced in Egypt, beside giving a quick idea about other modern brick types that are produced nowadays in Egypt. (I-1) Unburnt Sun-Dried Brick (Mud Brick) Ancient Egyptians used clay deposits in river Nile bed and banks as the first building material for their constructions since the very early ages in history and pre-dynastic periods. They made from it the mud brick, which is also called: unburnt sun-dried brick and adobe-brick (2). It is the simplest type of all brick kinds, which still is produced and used in some villages in the countryside of Egypt. Mud bricks are mainly made of river Nile clay deposit, which is a natural mixture of silt and clay beside other organic matters and minerals such as calcite, gypsum, but in small ratios. It is available in the river banks and the surround agricultural lands. That type of brick is used for building simple houses using mud-mortar in binding the bricks and plastering. (I-2) Fired Clay Bricks (Red-Bricks) Red bricks have been firstly manufactured and used in Egypt since the Romans era, and through all successive periods like Islamic periods, till today. Ancient Egyptians did not burn the mud bricks to produce this type, although their knowledge of heat and kilns which they used in glass and pottery manufacturing. This because they had sanctified and respect river Nile with its water and products, beside the other advantages mentioned before, which satisfy the Ancient Egyptians for building their houses. Like mud-bricks, red-bricks are also produced of natural clay which is available in Egypt’s agriculture lands and the area near the banks of river Nile. The manufacturing of red-bricks have been greatly developed in the present time than the original methods that were used during historical periods, as most of nowadays plants utilize mechanical techniques in most of the manufacturing process, although the same principles are still the same.

2

Thakib, F.H.,: “The Civil Constructions”, Educational Books, Part I, 2nd Edition, Assuit University, Al-Amirya Press, 1965, pp. 10-17.


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(II) Stone Masonry Units Stone is one of the most durable main building material man used through all historical eras, since the pre-dynastic periods of Ancient Egyptians and other early civilizations, till the present time. Most of survived historical buildings in Egypt and other countries are built of stone masonry. Stone masonry is usually used in the main structural elements (foundations, load bearing walls, piers, vaults, minaret’s base etc.) in most of religious Islamic buildings in Egypt, such as mosques and madrasas, for its eternity.

Geological background and definitions Rock: It is a natural and non-homogenous mixture of minerals which builds up the solid crust of the Earth. Stones: They are rock materials, which have been already quarried and cut in the form of great blocks, with random shapes and sizes. They are quarried from the surface (open bits) or the deep mines under the ground surface(3). They may be classified into the following types: Dimension Stone: It is a stone that can be cut and worked to a specific size and shape (i.e. in the form of block) of certain dimensions suitable for using as a building stone. Such stones should be found in large quantities in the mother rock, that can be mined in large blocks, and free from fractures and harmful minerals which may break down chemically or by other weathering factors, such as gypsum. They should also possess homogenous properties (as possible), pleasing colour, deformable, relatively hard and structurally strong. Almost all kinds of rocks can be used as dimension stone, depending on their usage in building, the aesthetic appeal and other aspects and considerations. Fabricated (Worked) Stone: They are stones which are cut and dressed manually or mechanically to be used as an ornamenting element for art or architectural purposes. Stone masonry works Stone masonry construction may be classified as follows: 1) Rubble Masonry Works 2) Stone Blocks In Courses 3) Ashlar Masonry

Rubble Masonry Construction In this system, construction is carried out using one of the following system: i) Random Rubble Stones These stones are used in the form at which they were cut from the quarry, undressed, it is commercially known in Egypt as “Ghasheem” stone. ii) Squared Rubble Stones

3

Abdel-Hady, M.,: “Conservation Of Stone Buildings”, Diploma of conservation lectures, Cairo Univ., Faculty of Archaeology, Conservation Dept., 1993.


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Stones are cut in a polygonal or prismatic shapes, which are slightly dressed. These types of stones are random in size, shape and dressing, but its height would not exceed 25 cm. Each of the previous two types may be erected in one of these methods: a) Uncoursed Random Rubble Stones Random stones are arranged in its undressed form without courses. The following points are respected in this system (4): 1) No continuous vertical mortar joints are allowed 2) Voids are filled with mortar and fragmented stones. 3) Bigger stones are put on the wall quoins. 4) Each 1.0 m2 of the wall surface should include one through stone, that extended through the full thickness of the wall. Two headers should also be included in each 1.0 m2 of wall surface, extend to half of wall thickness. b) Coursed Random Rubble Stones The rubble stones are built in courses, each of height about (30-40 cm). Each course may contain two or more large stones. c) Uncoursed Squared Rubble Stones (5) Slightly dressed stones are arranged in the construction randomly, uncoursed. Voids and areas created among stones are filled with “Snecks”, which are small rough stones. d) Coursed Squared Rubble Stones Previous stones are arranged in courses. e) Polygonal or Rustic Rubble Stones The apparent surfaces of stones are dressed to a polygonal forms. f) Coursed Regular Rubble Stones The dressed regular rubble stones are erected in courses, where each course contains stones of uniform height (almost the same) although, different successive courses may not be of the same height. In all the previous methods, the only visible sides of stone are slightly dressed, leaving the hidden sides (back sides) untreated in its original texture. Stone Blocks In Courses (Thal-ath) All sides of stones are dressed (but not completely finished to smooth surface). Its construction is similar to the “coursed regular rubble” method, but stones’ height is bigger in this method (6).

Ashlar Courses Construction (Dastour) (7) All sides of stones are finely dressed and finished to nearly smooth surfaces and all edges are sharp and complete. The resulting blocks are similar to brick units in their uniformity. The complete dressing costs more than any other previous construction methods, thus Ashlar stones are used merely in facade and important visible sides of masonry walls in special locations and rooms of the masonry building. Mortar joints of Ashlar system are thin (1-2 cm thickness). Besides the previous categories of stone masonry construction systems, the cross-section of walls may be classified as follows (8):

4

Thakib, F.H., Op. Cit., pp. 40-41. Thomas, K., Op. Cit., p. 295. 6 Thakib, F.H., Op. Cit., pp. 44-45. 7 Ibid., pp. 46-48. 5


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i)


Single-leaf wall: its thickness is composed of one block.

ii) Two leaves without connection: the x-sec. of wall is composed of two layers (walls), outer and inner, only connected by mortar in-between. iii) Two leaves with connection: the x-sec. of wall is composed of two layers (walls), outer and inner, but this time connected through the interlocking of blocks, beside the adhesion of mortar. iv) Three leaves: the x-sec. of wall is composed of three layers: outer, inner and infill rubble (similar to plain concrete as it composes of rubble stones or broken bricks and mortar) connect in-between. The following figure (1); shows all the previous discussion of masonry construction systems.

(III) Mortars: They are artificial mixtures, each is composed mainly of a cementing material (which may be gypsum, lime, Portland cement, etc.), and a filling material (sand). Other materials (additives) may be added in a certain limited ratio, to enhance the properties of the resulting mortar. These constituents are added to each other with a certain determined ratio, in proportion to their volume or weight, then mixed properly dry. At last, water is added to the previous mix in a proper amount, and then the whole mixture would be manually or mechanically mixed for enough periods, to finally produce mortar. Uses of Mortar in Masonry Construction: 1) Provides a uniform bedding layers for the structural masonry units, which helps to uniformly distribute their internal forces over the hole bedding layers. 2) Keep the masonry units in the desired place (ease units positioning). 3) Provide sufficient strength to support loads imposed up on it. Filling joints and voids between and inside masonry units.

8

Binda, L. et al.; “Structural Behavior and Durability of Stone Masonry”, Saving Our Architectural Heritage, The Conservation of Historic Stone Structures, Dahlem Workshop, Berlin, March, 1996, John Wiley & Sons Ltd., UK, 1997, pp. 119-121.


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Figure (1): Stonework Construction Types (After: Thakib, F., PP. 40-47).


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Mortar types There are many types of mortar used in historical buildings, which are: 1) Mud (Clay) Mortar. 2) Gypsum Mortar. 3) Lime Mortar. 4) Qusrmil Mortar.

5) Homra Mortar. MUD (CLAY) MORTAR It is the earliest mortar type found in Ancient Egyptian buildings, which was made of river Nile mud soil, (composed mainly of: clay, silt and loam). It is found in the Nile Valley, (its agricultural lands and river banks). This mortar was prepared of mixing clay soil, sand and small amounts of lime or gypsum, with the addition of chapped straw to make the mixture more plastic. The constituents are mixed with water to produce clay mortar. This mortar was merely used with adobe-brick masonry buildings, as a binding mortar between bricks or as a plaster(9). It has very poor strength and durability to weathering conditions. GYPSUM MORTAR Gypsum mortar is one of the eldest mortar types, it has been used since very early ages in history. The manufacturing and use of gypsum in Egypt was discovered since the early ages of Ancient Egyptians, and was used during all the successive periods till today. It is used in bedding mortars in stonemasonry works, plasters and other uses such as white colourant (pigment). LIME MORTAR The manufacture and use of lime for mortar and plaster is an ancient art. It was first used by the early Romans, and has been used ever since in all the successive periods all over the world until nowadays (10). Its use had spread in all masonry buildings during all Islamic periods in Egypt, for mortar and plaster works. Nowadays, lime is used for mortar, plastering and external rendering, as used in the past. *The Uses of Lime in Mortars: 1- Main binding material (cementing material): Lime is used in mortars after being slaked completely in water. Slaked lime (or lime putty) is mixed with sand in a certain proportion (i.e. 1:3) by volume. Then water is added and the whole contents are thoroughly mixed. This is the most prevail mortar in the historical Islamic masonry buildings.

2- Lime as additive: Lime is added nowadays to mortars of different cements (i.e. Portland cement) to provide the resulting mix good plasticity, water retentivity and reduce its shrinkage. ‘QUSRMIL’ MORTAR The ash results or by-produced from ovens, kilns, firing waste matter, etc. is working as a cementing material in mortar. It is mixed with sand and sometimes lime in proper proportion. The

9

10

Shaheen, A.A.,: “ Restoration and Conservation of Historical and Monumental Buildings”, Hundred Book Series, Supreme Council of Antiquities Press, Cairo, 1994, p. 82. Thomas, K., Op. Cit., p. 29.


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sulphate content should not exceed 0.5 %. This mortar was very common in historical Islamic architecture in Egypt, specially the brickwork masonry. THE FIRED CLAY MORTAR (HOMRA) It is produced from powder of good and pure burnt clay with minimum amount of impurities as much as possible. This burnt clay powder is taken from the grinding and pulverizing of broken redbricks, which are unqualified to construction uses; due to manufacturing defects (cracked, broken, ..etc.). The homra powder should be of fine grain size (pass through 2-mm sieve), and free from sand, ash, organic or any strange materials. It is also common in historical Islamic brickmasonry buildings. When adding a percentage of slaked lime to homra powder, we’ll obtain a good cementing material similar to hydraulic lime, but cheaper in cost. The former two types of mortars are still in used nowadays but in very scarce scale. They have high workability and plasticity but its strength is generally weaker than the other types, thus they result in weak strength masonry works. They may cause salt problems due to high impurities content.

Mortar joints: Mortar joints in masonry works are categorized and shown in the following figures: After the erection of masonry works is completed, the exposed outer surface of mortar joints are finished in one of the previous forms in order to: 1- To increase and complete the adhesion of bedding mortar to masonry units. 2- The resist the weather condition and its voids. 3- It helps to aerate (ventilate) the masonry work, as inner dampness can go out through it, and thus over come the salting problems associated with preventing the inside-wall dampness from release to enhance the appearance of the walls, in case of not rendered works.


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Figure (2)

General Mortar Joints (After: Mulligan, p. 141).


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5.1.3 Construction Techniques in Egypt 5.1.3.1 Greek-Roman Architecture in Egypt Historical background By 331 B.C, Alexander the Macedonian had already captured Egypt, When the Macedonian conqueror Alexander the Great entered Egypt, he was welcomed as the son of the god Amun and he was immediately accepted as the new king of the country (Empereur, 1998). He founded a new city on the shores of the Mediterranean in 331 B.C, the first of many cities to bear the name of Alexandria. He also set about restoring all the damage done by the second Persian occupation. (Dolphin et al, 1977). Upon his death 323 B.C and the death of his two Macedonian successors Phillipos Arrhidaeos and Alexander IV, his empire was divided between his generals. Ptolemy took son of Lagos, who had been appointed to satrap of the country by Alexander himself Egypt. During the wars that resulted from this division, he was also able to conquer Syria and Palestine. (Brink, 1986). Building of new temples throughout the country. On the island of Philae, Ptolemy II Philopator started with the rebuilding of the 26th Dynasty temple of Isis; his successor Ptolemy III Euergetes I started with the building of a new temple dedicated to Horus and decorated the propylon of the temple of Khonsu at Karnak. Their successors would continue to enlarge these temples next to building new ones such as the temple of Hathor at Dendara and the temple of Khnum and Neith in Esna. This way they ensured the support of the Egyptian clergy and the Egyptian people. (Davis 1960). During the reign of Ptolemy V, there was some upheaval when an Egyptian Dynasty tried to seize power. (Iskander et al, 1965). The dynastic rivalry of the later Ptolemies finally resulted in an intervention of the Romans to put Ptolemy XII Euergetes II back into power. From then on, the Romans began to play an important part in Egyptian history. They again intervened, this time in favour of Ptolemy XII’s daughter Cleopatra, a couple of years later. Although Cleopatra was a capable and a politically gifted ruler, she would become involved in the power struggle of the Romans Octavianus (Augustus) and Antonius and unfortunately, she chose the wrong side. When she and Antonius’ fleets were destroyed at the battle of Actium and she committed suicide, Egypt became a Roman province. (Bard, 1999) The Roman emperors too, continued the policy of building temples in Egypt, thus ensuring the loyalty of the Egyptian clergy and a stable flow of grain out of the greatest granary of the world. The beginning of the Roman Period is one of the most prosperous in Egypt: new cities were built and the land was considered of great importance to the world. As part of the Roman Empire, Egypt was also more open to the world than before. Although it had admitted its share of foreigners in the past, it had always clung to its own culture and to its own ideas. Since the conquest by Alexander the Great, however, it became more and more a Hellenistic state, with a Hellenistic culture, and as a Roman province, it was more open to the ideology that would finally strike the mortal blow to the millennia old Ancient Egyptian civilization: Christianity. (Arnold, 1999). Ptolemaic temples: construction techniques • Around 800 B.C., there was an increased interest in the historical past, perpetuated by people like Homer who told stories about the heroic past of Greece (David; Zink, 1979). • Greeks wanted to emulate the style of their ancient heroes, and were given the chance through increased interactions with Egypt. • Around 660 B.C., the Greeks had given support to Pharaoh Psamtik, who regained control of Egypt from Assyrian control. His victory opened the door for increased trade and


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• • • • • •


communication, and the Greeks founded a trading town named Naukratis on the western Egyptian coastline around 620 B.C. Egypt built monumental works completely in stone, and the Greeks eagerly studied their techniques in order to develop their own style. From the early seventh century onward, they would have had new knowledge of how to dress stone as well as how to physically put up such megalithic buildings. One of the easiest comparisons between Greek and Egyptian architecture is the Doric order (Paternosto, 1989). The Greeks at first closely followed the Egyptian models, although in their earlier temples it can be seen that they still needed to develop their refinement. But although the Greeks did copy some of Egyptian building techniques, their buildings in whole were very different from their Egyptian counterparts, keeping to traditional Greek forms. Note that the Temple of Isis, on the island of Philae which is one of the earliest examples of Greek megalithic buildings in Egypt, has monolithic columns. This would later be refined by building the columns up in drums rather than trying to carve the entire pillar, which took larger pieces of stone and so was both more expensive and more cumbersome.

The architect’s job •

In Greek-roman era in Egypt, there was no difference between architect and engineer until the late fourth century, and he was the most important person on the project, sometimes even more so than the patrons themselves. • The architect of the building project was expected to control all details of workmanship, inspect each course of stone before the next could be laid down, approve the tightness of each joint and the quality of the clamps, and authorize payments to all the workmen and contractors. In fact, the only part of the building process which he had no direct control over was the quarrying process (Morton, 1998). Quarrying and initial carving: • • • • • •

After the 6th century BC, the Greeks followed the Egyptian method of quarrying. Blocks were cut from the quarry on order from the builder, and even column drums were sometimes precut in their cylinder shape. A channel would be cut around the block to the depth of the height required and then it would be detached from its base with wedges. As Greek masons and architect refined their work, temples (it was mostly temples that were built with the best stonework) grew in size to a more monumental scale. As the temples grew, so did the size of the required blocks if the style was to remain in the same proportions. To ease the growing pressures on lifting and transportation, stoneworkers would often hollow out parts of the stone that weren’t essential to the support of the building (Hancock, 1998).


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Hollowed and extended beams: sections with oblique projection: a) lintel of temple. B) Architrave of temple. c) Architrave of Athenian treasury) column drum. e) Ceiling beam) cross-beam.

Transporting the stone • • • •

Most blocks could be transported to the build site in ox-drawn wagons, and this was the standard practice. The Greeks did at times use the Egyptian method of having blocks moved on sledges and rollers, but it wasn’t practical for long distances, and took too many men to execute properly. At times though, loads would become too heavy for wagons, and new plans would have to be worked out. Some worked while others not so much. Lower left design was actually used by the architect Cherisphron to move the architrave blocks for the Temple of Artemis at Ephesos (c. 560 BC) (Coulton, 2009).


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Lifting and leveling • • • •

Once the blocks had arrived at the construction site, the real work began. The Greeks did employ the earthen ramp method of the Egyptians, and even improved on the idea by using sandbags instead of earth so that once the stone block was in place, it could be lowered by a controlled flow of sand as they loosened the bags one by one. A preferred method though, was the use of cranes, much like the cranes we have today except made mainly of wood and rope. These cranes made it possible to have only a small workforce of professional workmen on the site, rather than the large mob it would take to use other methods like the earth ramp, and so was much more efficient and reasonable in a society which didn’t have the instant workforce which a pharaoh would have (Tomlinson; Richard,1992).

Lifting and leveling II: • • • •

The cranes, however more efficient than ramps, could only handle smaller sized blocks. Multiple cranes could be used on one block, but architects adapted to the machinery instead by having the same structure made of smaller individual units. U-shaped notches or protruding bumps would be carved into the stone pieces so that ropes would have somewhere to attach to when the block was lifted into place. Once the blocks were set in place, as well as during initial carving, masons would check that the blocks were level using an A-shaped level. This level had a plumb-line hanging from the apex, which on a level plane would hang directly between the two legs (Reynolds, 2009).


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Connecting and Finishing: • •

• •

The column drums were connected by metal dowels which were fixed with lead, and the regular blocks of the walls were fixed by metal clamps and lead as in general horizontal masonry practices, with no mortar used. Another construction feature commonly suggested as an earthquake preventative is the means used to join huge blocks together. It is believed that copper (or silver) was used at Tiahuanaco (below), both of which are soft metals. It has also been suggested that these 'ties' were employed to 'ground' structures properly (often made of conducting Quartzite). To make sure everything looked regular and aligned properly, the final carving was saved until all the blocks were in place. The stone was worked down with chisels until it was finally smoothed by small stones and sand. If it was marble, it could be further polished with leather.

Completely finished stones seemed to be reserved for only the most important buildings, as it took a lot of detailed work.


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a) The U-Shape holes on top, here for levers rather than cranes because of the small stone size. b) The dove-tail clamp connecting the top of the two stones c-f)

Preliminary finishing.

Ancient polemic columns in Egypt attract scientific attention not only on the basis of their specific flexibility, support and joint connections properties, but primarily, due to the force transfer mechanism between the columns parts that is achieved through wooden or steel pins (called ‘empolia’). In fact, this construction practice of finite strength that does not exceed the compressive strength of the connected drums is an early version of the capacity design process that is currently Damage based selection of techniques

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used for the seismic protection of structures. Nevertheless, this is a very complex and multiparametric problem that involves both geometrical and material nonlinearity; relative sliding and rocking of the drums, the role of non-uniform friction and the variation of axial load as well as potential emplolia fracture lead to a coupled and frequency dependent dynamic response under earthquake loading (Konstantinidis; Makris, 2006).


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'Folded' corners Several structures show the blocks cut with an internal angle, so as to 'fold' the stone around corner's. It is suggested that this was incorporated as an earthquake 'preventative'. There are several stones with this design feature in the valley-temple. It is interesting to note that the stones have been cut so as to continue only a short distance around the corner which hints at the idea that style might have been involved (rather than, or as well as, function).

Multi-facetted stones: It is often suggested that this design feature was incorporated into constructions as an 'earthquake' preventative. The fact that the constructions exist in such good condition after so long, in itself supports this idea. Temples versus secular: • • •

Ptolemaic temples were unique to Greek architecture in that their form never changed much. It was always a post and lintel structure, mimicking the homes of the early Greeks. This is somewhat misleading, because the Greeks did know about other construction methods such as the arch, they just chose tradition instead of new forms. In fact, the arch and other more experimental forms can be seen in secular structures. The arch in particular, was saved for structures with thicker walls, which would provide the proper amount of buttressing for the outward thrust.

The technology they used has stood the test of time and some Roman construction methods are still used today. The arch is an prime example of Roman technology that is still used world wide even though modern materials are now used. A basic example of the construction of a typical Roman Stone Arch is shown below. A wood frame was first constructed in the shape of an arch. The stone work was built up around the frame and finally a keystone was set in position. The wood frame could then be removed and Damage based selection of techniques

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the arch was left in position. Stone arches are not built entirely from stone. Stone is as expensive today as it was in Roman times. The Romans had a great understanding of material costs and consequently constructed stone structures from a combination of materials. The diagram below shows that accurately cut and shaped stone was used for the external walls. Gravel, sand and rough stone was used to fill all cavities. This filling was cheap to produce and use, compared to cut stone and it could be used by unskilled labour to fill the cavities of structures such as bridges and aqueducts (Salder;Simon; 2008). Quarry-Marks (for splitting stone) The megalithic builders employed the same method of splitting quartz, at different locations all around the world. This is not unusual, as it is probably the best method, and is still widely used today.

It is possible to see how the process of smoothing off of the granite casing stones was started on the Eastern face of Menkaures pyramid. The smoothing process was achieved with the use of Dolerite mauls which were able to pound the softer granite. This process can still be seen today at the Aswan granite quarries, where the granite for Giza originally came from.

It is perhaps surprising to find that some of the earliest known examples of masonry exhibit a sophisticated understanding of joinery. This particular construction feature is reasonably explained as having followed the transition from building structures first from wood then stone.


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Some examples of the Various 'Mortise and Tenon' joins used in the construction of The Osirion, at Abydoss, in Egypt. This is considered one of the oldest buildings in Egypt, and is quoted as having only one other structure of contemporary design, that being the Valley-Temple at Giza and still in use until the Ptolemaic era. Both structures used the technique of continuous-lintelled trilithon's, seen also at Stonehenge III. Ptolemaic temples in Egypt Temple for Sobek and Haroeris at Kom Ombo The Ptolemaic temple for Sobek and Haroeris at Kom Ombo. The god Sobek is represented as a crocodile. Haroeris is a form of the hawk or falcon deity Horus. If you are on deck at the right time you will to see, as we round a curve, this temple overlooking the Nile. We dock in front and walk up to the temple.

The temple of Montu at Medamud The temple of Montu at Medamud is, like its counterpart at Armant, in quite a ruinous state and is not officially open to the public. The present temple is a Ptolemaic/Roman temple, but it is built on a much earlier temple, possibly started by Senosret III in the 12th dynasty. It was connected to the Precinct of Montu at Karnak, by an avenue of sphinxes, over 8km long. The beginning of that avenue is reasonably well preserved. The temple is not easy to find, being in a mainly agricultural area, but is worth the effort of getting there. The temple is dedicated to Montu, Rattawy (the female version of Ra, and Montu's wife) and Harpocrates (Horus as a child).


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Temple of Horus The main attraction here is the Temple of Horus, which is considered by most to be the best preserved cult temple in Egypt. According to the Egyptian myths it was the place where the falconheaded god Horus avenged the murder of his father Osiris by killing Seth.

Esna Temple Rear of the Esana Temple of Knuhm. This temple was largely constructed by the Ptolemeys but all the reliefs were finished by the Romans. The temple was largely burried under the town and some parts still remain burried. The temple would normally continue from where this picture is taken. It is unique in that all the columns in the Hypostyle hall are different. Also, cartouches for most Roman empire.


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The Temple of Isis The Temple of Isis have a beautiful setting on an island. The views are great as you arrive by boat. The temple was mostly built during the reign of Ptolemy II Philadelphia (285 - 246 BC) on Philae Island and Isis was worshipped there until the temple was closed in 550 AD.


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5.1.3.2 Greek-roman Rock-cut Tombs: Construction Techniques and materials Damage based selection of techniques

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Two building types dominated Greek-roman architecture in Egypt; tombs and temples Tombs were most outstanding architectural element of the greek-roman period in Egypt. Tombs also serve as the focus for the worship of the dead. Minimal attention was paid to houses. Effort was dedicated to buildings associated with the religion and afterlife. So tombs and temples were design to last forever. The construction varied during the greek-roman periods in Egypt. Two types dominated Rock cut tombs and Shaft tombs. Rock cut tombs were carved out of existing mountains or hills like El-Shatbi necropolis, El-Anfoshi tombs, Mustafa Kamel tombs, Ras El-Tin tombs. Shaft tombs were dug in the underground of mountains or hills like Catacbombs of Kom ElShoqafa, Serapeum temple and ancient annex library. Catacomb of Kom El –Shoqafa The subterranean cemetery is the largest roman funerary complex in Egypt and the most important in Alexandria. The principal hypogeum of a funerary complex dating from the end of the 1st century of the Christian era, it was still in use at the beginning of the fourth. (Hassan, 1998). Kom El-Shoqafa is the Arab translation of the ancient Greek name lofus kiramaikos meaning “mound of shards” or potsherds its actual ancient Egyptian name were Ra-Qedit. The Catacombs lies in the district of Karmouz on the south-west of Alexandria and not far from the so-called Pompey,s pillar, there is found on the south slope of the hill. The area was called Kom El-Shoqafa or a pile of shards. (Baikie, 1973) This cemetery dates back to the 1st century A.D and it was used until the 4th century A.D. It was discovered in 1900, when by pure chance a donkey drawn cart fell into a pit, which led to the discovery. The word Catacomb means underground tunnels. The ones in Alexandria are called the catacomb as well because its design was very similar to the Christian Catacombs in Rome. Most likely, it was a private tomb and later converted to a public cemetery. It consists of three levels cut into the rock, a staircase, a rotunda, the triclinium or banquette hall, a vestibule, an antechamber and the burial chamber with three recesses in, where in each recess there is a sarcophagus. The Catacomb also contains a large number of Luculi or grooves cut in the rock. (Empereur, 2003).


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El-Shatbi Necropolis El- Shatbi Necropolis is the oldest in Ptolemaic Alexandria. Unfortunately, little remains of it. There is an El-Anfoushy type tomb group close to the road. Another kind of tomb, called a “surface tomb”, was discovered in the same area. These tombs usually contain pits with funerary urns for the ashes of the decreased, above, which are raised small monuments like stele or painted reliefs, (Hassan, 1998).


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The Necropolis of Mustafa Kamil Damage based selection of techniques

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The tombs of Mustafa Kamil date from the late third century to the second century BC, (Hassan 1998). They consist of rock-cut tombs located in the northeastern part of the Mustafa Kamil quarter. Unfortunately, the upper part, which used to be above the level of the ground, has completely vanished.

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Amod El-Sawari area (Pompey’s pillar, the ancient library and the Serapeum temple) Amod El- Sawari area has two Greek-Roman archaeological sites, namely the library and the Syrapium temple 245 B.C. This area was discovered in 1944.The so-called Pompey’s Pillar is the biggest memorial column in Egypt. It is a huge column of red granite, its total height is about 28 m with a diameter at the base of 2.7 m, and towards the capital at the top it tapers to 2.3 m. on the upper part at the western side is an inscription in Greek, which can be read” To the most just Emperor, tutelary of Alexandria Diocletian, the invincible, Postumus, the Prefect of Egypt (has erected this monument). The Roman ruler of Egypt during the reign of the Roman Emperor Diocletian erected this memorial column between 284-305 A. D in honor of his Roman Emperor as a sign of gratitude. A serious revolt in the city took place and Diocletian came himself, ordering the city to be besieged, after 8 months of resistance the city finally surrendered. As a result of the siege there was a famine in the city therefore the Emperor ordered that a portion of the corn, which was sent to Rome annually, be given to the people of Alexandria. He exempted them from paying taxes during these hard times. For that they erected in his honor this memorial column. In the middle ages, the crusaders believed mistakenly that the ashes or the remains of the great Roman general Pompey were put in a pot and placed at the top of the column. Thus, today it is called Pompey’s Pillar.


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5.1.3.3 Islamic architecture in Egypt- construction techniques and materials HISTORICAL SUMMARY AND CHRONOLOGY OF ISLAMIC EGYPT Egypt is a great heritage country which history extends to thousands of years of human civilization. This long lasting history has left through its periods a great wealth and heritage for mankind of monuments, artifacts and buildings, that witness and tell the various features, styles and conditions (political, social, economic, ..etc.) of its period. The Egyptian history includes many several periods and eras. In this research try to cover just a glimpse over some parts of its Islamic periods in Egypt, defining its general features and dates, but not a brief study. In fact, the historical studies are very important for the field of conservation and restoration of monuments, historical buildings and towns. Any relevant studies for such monuments should start with historical research and survey. 1- Early Islam or "Caliphate" Period (Umayyads, Abbasids And Tulunids Periods): When the Muslim conquered Egypt (20 A.H./ 641 A.D.), leader 'Amr ibn al-As established "al-Fustat north of the Babiluon wall, and so al-Fustat became the new Egyptian capital instead of Alexandria which remained as a capital since the Greek, through Romans and until the Byzantines. The first structure ibn al'As founded was his congregational mosque situated in the same location of the existing 'Amr Mosque in Misr al-Qadima district south of Cairo. Al-Fustat continued to be the capital of rule in Egypt during both 'Caliphate' and Umayyad period. When the Abbasid dynasty took over the rule, "al-'Askar" suburb was founded north of al-Fusjat (135 A.H./752 A.D.) until Ahmad ibn Tulun declared the independence of Egypt from the Abbasid dynasty and established the Tulunid dynasty which included Egypt and part of Syria; he then started construcing a new settlement al-Qata'i' to the north of al-'Askar (256 A.H./870 A.D.) of which the most distinguished' building was his big mosque founded (263-265 A.H./876-879 A.D.) and still exists until today. The Tulunid dynasty came to an end by the Abbasid leader Muhammad ibn Sulaiman al-Katib (292 A.H./904 A.D.) who completely demolished al-Qata'i'. and what only remained was Ahmad ibn Tulun mosque and so Egypt returned under the rule of the Abbasid dynasty and the capital was relocated in al-Fustat once more.

2- The Fatimids Period: When the Fatimid took possession of Egypt during the rule of al-Mu'izz Lidin Allah AI Fatiml and under the leadership of Gawhar al-Saqilli, the rule of the Fatimid dynasty started from (358 A.H./969 A.D.) until (567 A.H.l1171 A.D.) Gawhar al-Saqllli founded al-Qahira (Cairo) to the north east of al-Fustat and surounded it by walls, it was limited to the Faimids and forbidden for the public to live in, and so the foundation of Cairo did not affect by any means, the urbanization of alFustat; on the contrary, al-Fustat was filled up with various manufacturing workshops, houses and markets. By that time, Cairo cannot be considered as a part of the city but to be more specific it was more like a ruling castle and seat of the throne. It appears that the major reason which lead to this situation was the ideological difference the Egyptian Sunna and the new Fauatirn (Fatimid) Ismailian Shi'a. In this ruling center (al-'Qahira), al-Azhar was established as its congregational mosque (359-361 A.H.l970-972 A.D.) which still exists and functions until these days. The main spine in Cairo was named "Bain al-Qasrain" on both sides of which the most extravagant Fatimid palaces were situated.

3- The Ayyubid Period (1171-1250 A.D.):


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Salah al-Din al-Ayyubi, had established the Ayyubid period in Egypt in (567A.H./1171 A.D.), which lasted for about 80-years till (648 A.H. /1250 A.D.). ‘Saladin’; as known to western, started his rule by converting Egypt from Shi’i to Sunnism Islamic rite and uniting al-Qahira (Cairo) with the elder city al-Fustat, in one urban unit, specially after al-Fustat fire, which aimed to prevent its fall under the Crusaders invasion in ( 654 A.H./1168 A.D. ). He also succeeded to unite all Muslims to confront the Crusaders, whom already had invaded Jerusalem.(11)

Ayyubid period characterized by the following points : 1) The establishment of extensive fortified foundations, like al-Jabal Citadel and the city walls which extended to the new united city of Cairo/al-Fustat complex. These walls extended westward across the Khalij and eastward to al- Muqattam hill. (12) 2) The spread of building School system ‘Madrasa’ in Egypt, which had existed before, but in very narrow scale (very few number of madrasas were built in Alexandria during the Fatimid period and they were private ones) .Salah al-Din encouraged the spread of this type of pious buildings which aimed to counteract the Shi’i rite. 3) Salah al-Din also introduced the Monasteries ‘Khanqah’ system, as he had built the first of this pious foundation in Egypt. Although it had not survived it was considered as one of the most important khanqahs in Cairo for Sufis(13). 4) Salah al-Din, who died in 1193 A.D., had established a large dominion comprising: Egypt, Yemen, Syria, Palestine and northern Mesopotamia ‘Jezira’. This empire was split up among members of his family, the Ayyubids, at his death. The sixth Ayyubid ruler was al-Salih Nagm al-Din Ayyub, who introduced the practice of importing slave troops whom were called ‘Mamluks’. The Ayyubid period also witnessed splendour in public and cultural lives, and a long period of wars which were all reflected on architectural and urbanizing works(14) . Near the end of Ayyubid period, the whole Islamic empire was divided into different kingdoms ‘Mamalik’. Each of them had a separate army with its own ruling system, and their rulers claimed the rank of ‘Sultan’. The main Ayyubid centres were: Cairo, Damascus, Aleppo, Homs and Hama. They had continued in an uneasy alliance(15) between each other based on loosened family ties and the increased level of conflict among these kingdoms. 4- The Mamluk Period ( 1250-1517 A.D. ): On the death of al-Salih Nagm al-Din, his wife ‘Shagaret al-Durr’ had concealed that fact and taken charge of all affairs temporarily until his son ‘Turanshah’ returned home. Although the victory of Turanshah over the Franks at Faraskur, he was so hated by the Mamluks that they had finally managed to kill him after a reign of two months only. By this the Ayyubid period came to an end and the rule of Egypt moved back to Shagaret al-Durr for some time as the Queen of Muslims. But this idea of having a woman on the ruling seat of Egypt was not accepted by both Muslims nor the Abbasid caliph of Baghdad, who wrote to the Egyptian leaders threatening to send one of his leading Mamluks to take over of Egypt. So Shagaret al-Durr chose Izz ad-Din Aybak, one of the

11

- “Principles of Architecture Design and Urban Planning During Different Islamic Eras”, Organization of Islamic Capitals and Cities, Jeddah, Saudi Arabia, 1992, p. 418. 12 - Abouseif, D. B.; “Islamic Architecture in Cairo”, An Introduction, American University in Cairo Press, Cairo, 1989, p. 7 . 13 - Ibid., p. 11 . 14 Williams, C.; “Islamic Monuments in Cairo”, A Practical Guide, Fourth Edition, The American University in Cairo Press, Cairo, 1993, p. 11 . 15 Burgoyne , M.H., “Mamluk Jerusalem”, An Architecture Study, Published on behalf of the British School of Architecture in Jerusalem, by the World of Islamic Festival Trust, 1987, pp. 53- 54 . Damage based selection of techniques

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leading Bahri Mamluk and commander-in-chief, to marry with, and by this he became the Sultan of Egypt and the first of all Bahri mamluks. Soon, Shagaret al-Durr got so jealous of Aybak’s previous wife and his proposal to marry the daughter of Amir of Mosul, that she decided to get rid of him and had him murdered(16). The assassination of Aybak by his wife was too hard for his Mamluks that they had her imprisoned in the Citadel and after three days they handed her over to the former wife of Aybak who revenged for her husband and killed her. After a short time the rule of Egypt was taken by al-Zahir Baybars, an energetic ruthless mamluk, whose reign to Egypt (dated from 1260 to 1276 A.D.). He was considered to be the real founder of the Mamluk State in Egypt, by his defense of Islam against the Mongols raids and his victory over the Crusaders invasion in Syria(17). In general, at the death of the Sultan, rival amirs fight over the succession , often through the streets of Cairo until the strongest prevailed. The Mamluk period in Egypt was divided into two consecutive periods: a) The Bahri Mamluks ( Saljuks ). b) The Circassian Mamluks ( Burgi ).

i ) The Bahri Mamluk Period (1250-1382 A.D.) Their name was derived from the word ‘Bahr’ means river, so the word ‘Baharyya’ referred to the place where those mamluks resided and raised, which was al-Roda Citadel on the river Nile bank. Most of those mamluks were brought from the steppes of the river Volga near the Caspian Sea. (18) The period of Bahri rule was relatively prosperous for Egypt. The wealthy crossroads of trade and commerce provided the rulers with money sufficient enough to support a strong army and all other life fields (social, religious, art,..etc.). A succession of strong rulers maintained Egyptian control over Syria and eventually drove the Crusaders out from its mainland. Moreover they succeeded in repelling four major Mongol raids over Egypt, thus protecting Egypt from the crushing devastation of the befall Iraq and Syria(19).

The most important features of this era in Egypt was(20): 1) Continuous internal struggles between grand amirs and Sultans to take power by force and not according to the inherit system, as followed before during all previous eras. 2) Cairo became once more the Caliphate centre which enabled Egypt to produce its own styles of architecture and arts, and not just a follower as being a caliphate province. 3) The Mongol invasion raids which had overthrown Iran, Baghdad, Syria and Palestine, encouraged the migration of architects and craftsmen to Cairo, where stability and caliphate location. 4) High taxes and Iqta-a’ with extravagance in festivals and all other life features of Sultans, Amirs, and elite persons increased the internal political and social instability. 5) Different features and effects of architectural styles and foundations; such as: Madrasa, Khanqah, Sabil-Qutb, Baths and Khan, beside features from Syria, Persia, Iran, Andalusia 16

17 18 19 20

Creswell, K.A.C., “The Muslim Architecture Of Egypt”, Part II, Ayyubids and Early Bahrite Mamluk, 1959, pp. 135-138. Burgoyne , M. H., Op. Cit. , p.54 . Williams, C., Op. Cit., pp.14-15 . Creswell, K. A. C., Op. Cit., p. 139 . “Principles of Architecture Design and Urban Planning During Different Islamic Eras”, Op.Cit. pp. 418-420.


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and Christians countries; due to the great migration movement that took place during this period.

ii ) The Burgi ( Circassians) Mamluk Period (1382-1517 A.D.) The Bahri mamluks were followed by the Burgi mamluks, who were mostly Circassians from the Caucasus mountains and whose name was driven from, owing to the fact that they were raised in the towers of the Citadel, which called in Arabic “Burg”, that means tower. The Burgi mamluks ruled Egypt for about 135-years, the period ( 784-923 A.H./ 1382-1517 A.D.) (21) . Although Bahri period was violent and filled with wars, Burgi was more than that. Thus, it was an unhappy era in the Egyptian history, but this didn’t stop the architectural and construction achievements. On the contrary, its arts and architecture were very advanced and exceptional. The corrupt and arbitrary rule of the Circassians were the ruination of an economy(22) that suffered further from natural catastrophes; such as plague and drought from the breakdown of security in the outlying areas and from the discovery of a sea route to India by the Europeans. That was accompanied by the invasion of Tamerlane, who had reached as far as Damascus and destroyed most of what he found, but conquered by Egyptian army. The mamluk period was brought to an end by the Ottoman Turks under the leadership of Selim, who conquered Cairo and hanged the last mamluk sultan, Tumanbay in 1517 A.D. Apart from all these events, the Circassians period had left a big number of monuments and very fine arts. Sultans and elite persons had generously financed the architecture and art works, that resulted in highly ornamented and decorated elements; such as the floral and geometric carving of stone domes form outside reached its apogee. Although buildings were of limited (smaller) area in comparison with previous relevant buildings from previous eras, the high level of ornaments and decoration, with more advanced carving of stone masonry works (i.e. domes, minarets, etc.) were witnessed in most of this period architecture, as the Egyptian arts had crystallized and developed to a very advanced level. The Circassian period started with sultan Barquq (1382-1389 and 1390- 1399 A.D.). His son, Farag reigned for about six years after him. Among the following sultans of this period were: alMu’ayyed Shaykh (1412-1421), al- Ashraf Barsbay (1422-1438), al-Zahir Joqmaq (1438-1453), alAshraf Inal (1453-1461), al-Ashraf Qaytbay (1468-1469) and al-Ashraf Qansuh al-Ghuri (15031516) A.D. (23) The fifteenth century was considered as a period of social and economic decline. Agriculture revenues had decreased as the land under cultivation shrank. Taxation continued burdensome and arbitrary with damaging effect on trade and industry of towns. A general lack of security on lives and properties prevail everywhere. The whirlwind of invasion of Syria by Tamerlane and his Mongol and Turcoman armies was greatly destructive and the coastline of the Mamluk state was attacked by the Crusaders. All those factors beside the internal ones, all together had put an end to the declined Mamluk state by the newly born force, the Ottomans, who soon took over after their vectories at Marj- Dabiq near Aleppo in 1516 A.D. and at Raydaniya, north of Cairo in 1517 A.D. (24) 5- The Ottoman Period: It was considered the longest ruling period ever witnessed before in Egypt, which dated (923-1220 A.H. / 1517-1805 A.D.); i.e. about three centuries. The ruling system was divided among the Wali

21

“Principles of Architecture Design and Urban Planning During Different Islamic Eras”, Op.Cit., pp. 418- 419 . 22 Williams, C., Op. Cit., p. 15 . 23 Williams, C., Op. Cit., p. 17 . 24 Burgoyne , M.H., Op. Cit., p. 55. Damage based selection of techniques

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(Pasha), the military garrison and the mamluks. The wali represented the Ottoman Sultan in governmental, administrative and financial affairs and he also sent the tribute to the sultan(25). Under this Turkish rule, Egypt had returned to be a province following the ottoman caliphate. Financial and most internal Egyptian conditions got worse, in addition to that, the ottoman wali sent most of the talented architects and craftsmen to Turkey. Besides, he also sent Egyptian army to support the Sultanate army in their wars. The ottoman wali used mamluks to assist him in all ruling affairs as they were acquainted by people. These conditions had led to complete separation between people and their rulers. The agriculture life was destroyed and a continuous decline in the internal conditions. At the end of this period French invasion came to Egypt during (1798- 1801 A.D.), then Mohammed Ali ruling period and his descendants, followed by the English invasion till 1952 revolution which set Egypt free and it became independent.

5.1.3.4 General types of buildings Islamic Egypt During all Islamic periods different structures were built to serve certain purposes and functions. New types were innovated such as mosques, school (madrasa), sanctuary (khanqah), sabil-kuttab, ..etc. The surviving building of each type witness through its elements and decoration the different styles of each Islamic era, thus lay its great historical value. Historical Islamic Structures may be classified as follow : i) Religious Architecture (Pious Buildings) : -Mosque -School ( Madrasa ) -Sanctuary ( Khanqah ) -Dar-al-Ilm -Dar-al-Hadith -Dar-al-Qur’an Funerary Architecture (Memorial Foundation) : -Shrine ( Mash’had ) -Tomb ( Mausoleum ) ii) Public and Service Architecture: -Hospital ( Maristan ) -Sabil-Kuttab -Wekala -Khan -Bath ( Hamam ) -Libraries -Shopping centers and markets ( Qaisariyyat and Souqs ) iii) Residential Architecture: -Houses and Palaces vi) Fortification Architecture: -City walls and gates -Citadel -Ribat 25

“Principles of Architecture Design and Urban Planning During Different Islamic Eras”, Op.Cit., pp. 419420.


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v) Irrigation Structures: -Channels and Aqueducts Those are the most famous types of Islamic architecture founded in Egypt during all Islamic eras, however there still more. They are given as samples of its type. We are going to discuss these buildings types as the following. I ) Religious Architecture In Islamic Egypt The Foundation Inscription(26) It is difficult to identify the original purpose of many pious buildings because of the medieval names that was given to them by the historians were sometimes not accurate and haphazard, specially near the end of the Mamluk period, where the three main pious buildings (mosque, madrasa and khanqah) were very similar in planning and architecture. For instance, you can find a madrasa called a khanqah in the literature of old or contemporary historians. The only true document of the building function is its “foundation inscription” which can be found written or carved on stone strip (frieze) over one of the building main walls; such as the main entrance or the facade of the qiblaiwan. The function which the building served may had changed several times during its age. Of course, architecture is not a reliable guide to the building function, as most of pious building planning was similar and little of the variation in layout seems to be related to the function, beside the several additions and layering works that may have been carried out in the building. (1) Mosque: Mosque is the first Islamic foundation, which prestige, holiness, respect and function have been maintained and remained since the beginning of Islam and until today. It was started very simple, of mud bricks and palm leaves, and developed in area and architecture style increasingly with time. Because mosque was the only foundation that exist at the early Islamic era, all activities were carried out into it. Those activities were such as : -

Praying the five daily prayers and the Friday sermon. Teaching and reciting holy Qur’an. A court of justice. A place where Islamic troops and armies were set out for wars. A school to teach religious and secular sciences.

The Prophet mosque, in al-Madina, was the first formal one in Islam. It had no minbar, mihrab or any architectural refinement, but only a shaded area at one end (al-Qibla wall). This simple prototype (hypostyle) was respected in all mosques during the following eras, although they had differed in area and architectural styles, but the basic conceptual design; of a central courtyard surround by four shaded area; was maintained(27). Building a new mosque was a tradition of most rulers at early Islamic periods, after they had conquered any new country or established a new capital. They used to build a mosque and a palace (house of caliph) at the centre of the newly established capital city. With time, mosque area had increased with the increase in number of Muslims and the growth of Islamic empire. 26 27

Burgoyne, M. H., Op. Cit., p. 88 . Williams, C., Op. Cit., p. 20 .


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The ordinary mosque was called “Masjid”; which the origin of the word mosque. The congregational mosque was called in Arabic “Masjid-Jami’ ”and abbreviated as Jami’, which area is large enough to accommodate all Muslims during Friday sermon delivered by the local governor(28). At first, congregational mosque was the administrative, social and religious centre of the town. Every medieval urban agglomeration had its own congregational mosque, but when the cities and Muslim community had grown, the number of Friday mosques (Jami’) increased. As for example of this, al-Fustat had ’Amr mosque (Pl. 1), the Tulunid period had the Ibn-Tulun mosque (Pl. 2), the cities of al-’Askar and al-Qata’i’ each had its own Jami’(29).

Plan

The Entrance Plate (1): Amr Mosque

Plan

The Court Plate (2): Tulun Mosque

During the Fatimid period, Friday sermon was held in the main four mosques "Jami’":(Amr, IbnTulun) at the out side of al- Qahira and [al-Azhar (Pl. 3) and al-Hakim mosque] inside it. There is another type of mosques in the same period like Al-Aqmar mosque (Pl. 4) which used of praying the five prays of the day.

28 29

Abouseif, D. B., Op. Cit., p. 12-14. Ibid., p. 14.


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Plan


The Corte Plate (3): Al-Azhar

Plan

Section Plate (4): Al-Aqmar Mosque

While during the Ayyubids; the only congregational mosque of Cairo was al-Hakim mosque as it was the largest in the city by this time and ’Amr mosque remained the official one for al-Fustat. Each of those congregational mosques was the only official one at its time to held in it the Friday sermon. During the Mamluk period, the number of Friday mosques were increased and from the time of Sultan Hassan, madrasas (schools) and khanqahs were also used as Friday mosques, in addition to its main function(30). The reason for this was the great increase in number of Muslims to the extent that the official mosques could not accommodate all those people. Thus, by the fifteenth century, this system allow each quarter and even each main street to have its own mosque (Jami’). During the ottoman period the plan of mosque is a square prayer hall surrounded by a riwaq from three sides except for the qibla wall. The mosque has three entrances, with three other opposite entrances in the surrounding riwaqs. The ablutary is placed separately from the building block taking into account the climatic conditions for determining their locations such as Mosque of Muhammad Abu Al-Dhahab (Pl. 5).

30

Abouseif, D. B., Op. Cit., p. 14.


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Section

Plan

Main Elevation Plate (5): Muhammad Abu Al-Dhahab Mosque

Mosque remained during all periods the first and highest foundation respect. It remains the symbol of Islam and the place of all Islamic activities. *The Memorial Foundation Islamic funerary and memorial architecture were pious foundation that had spread in Egypt since the Fatimid period, although they were known in Egypt and other parts of the Islamic world earlier than this period, but on a limited scale. This type of funerary foundations included the following systems: One) The Shrine (Mash’had), Two) The Mausoleum and tombs a) The Shrine This type of foundations was introduced to Egypt by the Fatimids who dedicated those buildings to the descendants of Prophet Mohammed. Those descendants had died much earlier than those buildings and had no connection to Egypt at all(31). As for example of those shrines: the Sayyida Nafisa and al- Hussein shrines. The Fatimid rulers, who were Shi’a rite, aimed with the construction of such buildings to narrow the gap between themselves and the Egyptian people, whom remained faithful to Sunnism and didn’t follow the Shi’a rite of their rulers. Each shrine claimed to have one of worshipped saints buried in it, thus it was respected and visited on religious occasions and on the birthday of its saint. All Fatimid rulers and ministers had given the shrines a great deal of attention and respect. Thus, the prestige and respect of Fatimid rulers were enhanced as they constructed such venerated buildings although they were not buried in such buildings, but within coffins of their own palaces. The development of Shrines was the mausoleum, which took similar archi-tectural style of shrine but was attached to a certain religious building, such as madrasa or khanqah to gain the prayers to God by the students, their sheikhs (teachers) and the visitors to their religious building.

31

Ibid., pp. 10-11.


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b) The Mausoleum This funerary building was also called; “the tomb” or “Qubba” which means the domed mausoleum. This name because such building were often surmounted by a dome. The founder of the mausoleum and his family would be buried, at their death, into their mausoleum. The mausoleum (qubba) have always four (32) main parts which are: 1) The Burial Room: It is an underground room, usually with vaulted roof. The dead were buried into it following the Islamic tradition rules. Its access opening on its roof is closed by stone strips. This room is also called “Faskyah”. 2) The Mausoleum Square Room: It is the room above the ground surface which contain at its meddle the cenotaph or “tabut” in Arabic, which is a rectangular box-like structure of stone (i.e. marble) or wood, raised on a low plinth indicating the presence of a grave under the floor. 3) The Transition Zone: This part transforms from the bottom square room to the bottom circle of the upper dome. It was developed architecturally from both inside and out side, such as covered with stalactites as we’ll see later. 4) The Dome: It may be found rest on the transition zone directly or on a circular shaft called “drum”, that includes windows and ornamentation. The last three parts always above the ground surface thus visible rather than underground part.

the first

(2) The School (Madrasa): It was apparently at Nispur and Marwa in Iraq that school was first given the name of “madrasa” (33) . The construction movement of madrasas in Egypt remained local and limited with only four schools, were constructed in Alexandria, out of Cairo, which had been the Shi’a rite capital of the Fatimids, until the coming of the famous vizier, Nizam al-Mulk, vizier of three successive Seljuq Sultans in the period from 1038 A.D. to 1092 A.D. He was one of the greatest prime ministers and the first to realize the use of the madrasa system for the Sunnism rites publicity against Shi’a doctrines. Under him, it was raised from the status of a private school to that of a state control institution, with political tendencies as it became a colleges for training a selected body of officials for all branches of administrative jobs(34). Nizam al-Mulk had founded many madrasas in Persia and lower Mesopotamia, and his successors, such as Nur al-Din and Salah al-Din, who were princes, of Kurdish and Mongol origin and ardent Sunni rite, had followed his example to spread this institution over the whole Seljuq empire. Salah al-Din started construction his schools at Damascus in Syria and after he had overthrown the Fatimids, he spread these institution into Egypt to combat the Shi’a doctrines . Teaching theology and religious sciences started since the very early of Islam in mosques and continued with time in it, even after the innovation of schools and khanqahs(35). Among the congregational mosques that had kept its teaching function after school innovation, were: ’Amr mosque, Ibn-Tulun mosque and al-Azhar mosques. Sciences during the Islamic periods were divided mainly into two categories: Secular Sciences: such as mathematics, astronomy, geodesy, medicine, grammer, .etc. 32

33 34 35

Al-Hadad, M.H., “Domes in Islamic Architecture (Al-Quba Al-Madfan)”, Its evolution till the end of Mamluk period, Al-Thaqafa Al-Deenya Liberary, 1st. Edition, 1993, Cairo, p.55. Creswell , K.A.C., “The Muslim Architecture Of Egypt”, Part II, Op.Cit. p. 105 . Ibid, p. 106. Sameh, K.; “ The Islamic Architecture In Egypt”, 3rd. Edition, al-Hay’a al-Amaa Lil- Kitab (The Egyptian General Commity for Books) Press, Egypt, 1973, pp.9-11.


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Islamic Sciences: various branches of theology; such as “sunna” or rituals, “shari’a” or canon law, and Qur’anic sciences. The four Sunni rites of Islamic religion were founded by the following Imams: 1. Imam Malik : The Maliky rite. 2. Imam Abo-Hanifa : Tha Hanifya rite. 3. Imam al-Shafi’i : The Shafi’ia rite. 4. Imam Ahmad Ibn-Hanbal : The Ibn-Hanbal rite. These rites were established to judge some of the confused daily life affairs not mentioned in the two main sources of the Islamic religion, which are the holy Qur’an and the Prophet’s Hadith (the written words by the Sahaba of the Prophet after his sayings or his behaviour in different situations). Their opinions are optional for Muslim to follow as they apply the “Igtehad”; which is the grand sheikh judgment and opinions in religious affairs after the great and deep knowledge of Qura’an and Hadith . i) The definition of School ( Madrasa ): “It is a theological institution, built to teach mainly theology, following the Sunni rites, and sometimes law and secular sciences(36) such as medicine. It was endowed for one or two or four Sunni rites of which it was specialized in teaching it or them. Its students were prepared to undertake scholarly or administrative jobs in the country after their graduation. In addition to learning, they were given food, lodging, clothing and salaries (stipends). The school was also planned to lodge also the teachers (sheikhs) and had prepared salaries for them ”. Thus its main function was to provide its students, teachers and servants with a hostel to live and study, and a place to teach mainly the theology of the Sunni rites, as other branches of the Islamic sciences had got its independent foundation to teach them, such as “Dar-al-Hadith” and “Daral- Qur’an”. Although the congregational mosque had taught most the of the theological sciences of the madrasa, and its teachers (sheikhs) and students earned salaries prepared to them from the government on the later periods, it was not called “madrasa” because mosque didn’t have cells to lodge its residence. Besides, mosque was opened for all people to access rather than madrasa which access was allowed to its students and sheikhs, thus its planning was differed from mosque. ii) The Historical Evolution of the School (Madrasa) System in Egypt : 1. Nazim al-Mulk was the first one to fix and prepare the financial and planning system of the school. He turned it from a special foundation under the supervision of persons to a governmental one. He was also the first to fix salaries for sheikhs and students of his schools. His school planning was respected in the following periods as a prototype. His constructions had encouraged the Islamic rulers and viziers to build and take care of this type of religious foundation. His first school “Al-Madrasa al-Nizamia” was the turning point and a new era of all following schools. Following it, he had built many other schools in different places and towns, during the Abbasid period. He also made the Shafi’ia rite a formal one for the Abbasid reign to endow schools for. (37) 2. Salah al-Din during his period, since he was an Abbasid vizier till he became the Caliph and established the Ayyubid period in Egypt, he worked on spreading madrasa and khanqah systems in Egypt beside other buildings such as walls and citadels (fortified architecture). 3. Schools were built in Egypt by the Ayyubid to counteract the Shi’a doctrine which capital was Cairo during the Fatimid period. It also aimed that its graduates who would take

36

Sayed, A. F.; “Schools in Egypt before the Ayyubid Dynasty”, “Tarikh al-Misryen” Magazine, Number of researches and papers of “Nadwet al-Madares”, issue(51), The Egyptian General Commity for Books Press, Cairo, 1991, pp. 99-100.

37

Ashour, S.A., “Tarikh al-Misryen” Magazine, Op. Cit., pp. 15-44.


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administrative jobs, would be loyal and faithful to the ruler or the Grand Amir, as in Mamluk period, who built the school. 4. The foundation of schools were spread during the Mamluk periods greatly, and was carried out by rulers, grand amirs and other rich persons as a charity works. 5. The rite(s) and other sciences beside the whole system of the madrasa was fixed by the founder and remained under his inheritors control after him. 6. The function of madrasa had passed through three(38) main stages: The first stage was only to teach the rite(s) it was endowed for beside holding the five daily prayers for its residents. For this reason only a minaret was added to the building. The second stage; Friday sermon was held in some of the madrasas since the late Bahri Mamluk period, because of the great increase of Muslim number in time, until they made it difficult of the available mosques to a accommodate them. This recommended the additional of some elements of the congregational mosque to those madrasas such as “minbar”, “minaret”, “mihrab” and “dikket al-mobaligh”. To allow the holding of Friday sermon in madrasa it required the permission of the ruler (Sultan or Wali) and the founder permission as it was not allowed to set it back to be only school after this. This phenomena started at the end of Bahri Mamluk, and continued during the following periods. The third stage; the madrasa worked beside its function, as a khanqah for Sufis. iii) The Madrasa Architectural Planning: There are three(39) main architectural planning of madrasa (school) systems which are: 1) The Orthogonal Plan: It consisted mainly of iwans or aisles around a central uncovered courtyard (sahn) or central covered courtyard (durqa’a). The first type prevailed in most of pious buildings specially madrasas, form early Islamic periods till the end of Bahri Mamluk period, while the second had spread since the beginning of Circassian Mamluks era and the succeeding periods, resulted form the limited urban land available to build on, as no new cities were established after Cairo, but each one had grown more and more(40). In the orthogonal system, we find one, two or four iwans of different sizes, with vaulted masonry roof or horizontal wooden one (according to its span). There was no relation between the number of those iwans and the number of rites of which the madrasa was endowed for(41), for instance: two iwan madrasa may be endowed to teach four Sunni rites. Among the iwans, we find rooms and cells of sheikhs and students of the madrasa. The biggest iwan, as usual, was the Qibla iwan. Most of the madrasas where two-story masonry structures. Foreign architectural documents and historian descriptions always call the orthogonal (perpendicular) planning system as ‘Cruciform’; for they believe that this planning system is derived from the churches planning of previous eras, which our historians have proved that this theory is totally fault. In fact, the origin of this planning system was derived from the ‘qa’a’ system of the house (bait) hall. 2) Arcade areas around central Sahn or Durqa’a: It was similar to mosque traditional planning of central courtyard, uncovered (sahn), or roofed (durqa’a) surrounded by shaded areas called “Zolla”, composed of number of aisles extended parallel to qibla-wall, i.e.: Madrasa of Qanibay ( 845 A.H./ 1441 A.D.). 38 39 40 41

Al-Hadad, M.H., “Tarikh al-Misryen” Magazine, Op. Cit., pp. 285-307. Al-Hadad, M.H., “Tarikh al-Misryen” Magazine, Op. Cit., pp. 280-284. Williams, C., Op. Cit., p. 22 . Nowisar, H.M., “Factors affects the Mamluk Madrasa planning”, “Tarikh al-Misryen” Magazine, Op. Cit., pp.241-243.


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3) Arcade areas without central Sahn or Durqa’a: This system is composed of rectangular or squared shaded area divided into aisles or arcades parallel to the qibla-wall, with horizontal wooden roof, example: Al-Taybarsia Madrasa . Most of pious foundations follow the customary centralized plan, of the medieval times, that is composed of various chambers disposed around an inner courtyard. vi) Design Principles of Cairene Madrasas(42): * Ayyubid Period The madrasa was at first similar to mosque architecture. Muslim architect started to use vaulted iwan instead of aisle covered by timber roof. The plan took into consideration the street line in the external facade and the qibladirection in the internal configuration, which led to variable wall thickness. The general plan was composed of a central courtyard surrounded by two iwans; in the qibla direction and the opposite side, while on the other two sides lay students and rectors cells. Bent entrances, vestibules (darqah), and corridors appeared for the first time in the religious architecture. The number of entrances decreased. Facades were carefully studied and ornamented with floral and geometric patterns. In the forepart of the qibla wall, one or more recessed niches (mihrab) were erected such as Al-Salih Nagm Al-Din Ayyub (Pl. 6).

Section

Plan Minaret and The Entrance Plate (6): Al-Salih Nagm Al-Din Ayyub * Bahri Mamluk Period Madrasas included four iwans opening into an open courtyard. Cells and rooms were placed on sides of the court between iwans and came on two levels. In some rare examples, the plan included special cells and rooms for students and teachers of each rite (mazhab) next to its iwan. The mausoleum of the founder and his family was usually annexed to the madrasa. Bent entrances were built, and the main one was distinguished by the minaret rising on its top or at one of its 42

“Principles of Architecture Design and Urban Planning ...”, Op. Cit., pp. 474-476.


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sides. The ablutary was placed at lower level than the madrasa to preserve its purity and not to disturb the inhabitants with any odour. External facade was carefully studied and ornamented. Horizontal inscription and coloured stripped courses (ablaq). The facade also respected the street line while the internal configuration follow the qibla orientation, that results also in variable thickness walls. The qibla iwan incorporated a recessed mihrab and minbar, and the qibla wall was distinguished by ornaments rather than other madrasa walls- such as the Complex of Qalaun (Pl. 7), Madrasa of Sultan Hasan (Pl. 8).

Plant & Section Plan &Section

Main Elevation Plate (7): Complex of Qalaun


The Entrance Plate (8): Madrasa of Sultan Hasan

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* Circassian (Burgi) Mamluk Period The madrasa with iwans prototype still prevailed, but decreased in area. Its plan was composed of central courtyard which opens onto four small iwans or zollat; that divided into aisles, vaulted or covered with wooden roofs. The plan also included rooms for the residence of the founder’s family in some special occasions, beside the traditional cells for students and sheikhs. The development of the madrasa, was the appearing of the durqa’a system, that surmounted by a wooden lantern instead of the open court- such as Madrasa of Khanqah of Al-Zahir Barquq (Pl. 9), Madrasa of Al- Ghuri (Pl. 10).

Plan Entrance & Main Elevation Plate (9): Madrasa of Khanqah of Al-Zahir Barquq

Plan

Main Entrance Plate (10): Madrasa of Al- Ghuri

* Othman's Period The madrasa is designed as the elevated mosques, and has commercial activities in the ground floor, with an educational section in the upper floor. Sometimes madrasas contain a residential section, other times a sabil and a kuttab. The ablutary is sometimes placed in the center of the courtyard and other times adjacent to the lavatory which is separated from the building by being placed in a lower level taking into account the climatic conditions by determining its location in relation to the building. A separate entrance with different treatment for different uses is achievedsuch as Madrasa Al-Sulaimaniyya (Pl. 11).


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Plan

The Entrance Plate (11): Madrasa Al-Sulaimaniyya


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** The Commonly Elements which are found in almost all Cairene Madrasas, which are(43) – See (Pl. 12 & 13): 1- A Prayer Hall ( Sanctuary ): It includes the most important element in the school, which is the qibla wall, that Muslims face during all their prayers as it direct them to the Mecca direction (south-east). This qibla direction is respected in most of the interior walls and the whole planning of the religious building, that almost every room has a wall parallel to it, and this rule is a necessity in the main halls and iwans. The prayer hall is the most visible feature in the pious building which can be seen easily since you entre the building and from all its parts. It is the biggest hall in all the school and it is usually extended parallel to the qibla wall, or normal to it; in order to accommodate as much as possible of Muslims during their prayers, thus it was later used as a Friday mosque. 2- The Courtyard ( Sahn ) Every school has a central courtyard rectangular or square in plan, which called “Sahn” or “Bahow”. This area is vast with respect to the whole area of the school in order to supply it with fresh air and sun light for ventilation and light needs. Until the Bahri Mamluks, sahn was opened area (uncovered), but later during Circassian Mamluks, as land areas were limited caused by the congestion of buildings in the old towns without building new cities, the sahn became smaller and roofed like the “ Qa’a ” or hall in the residential houses. 3- Students and Sheiks Cells Those rooms surround the central courtyard (sahn) of the building, where teachers (sheikhs) and students live and study. The greatest room devoted for the grand sheikh, following it the rooms of the other teachers but smaller in area, until the students’ cells which were the smallest rooms in the building. 4- Mausoleum Almost all madrasas and khanqahs were attached by the mausoleum (tomb-chamber) of the founder of the building and his family. 5- Minaret It was a tradition that each school had its own minaret(s), although the great number of minarets of the nearby religious buildings and the need for it was not like in case of mosque. 6- Service Rooms Those rooms are such as: the kitchen, bathrooms, library, studying and meeting halls, ..etc. Definition of some elements commonly found in religious buildings : Iwan: It is a rectangular hall closed on three sides and opened on the fourth over the main courtyard (sahn) of the building with an arch. Qa’a: It composes of two opposite iwans, separated by a roofed courtyard, which called “Dorqa’a”. It is originally found in the domestic Islamic architecture, such as houses. Dorqa’a: It is the central roofed courtyard in the qa’a. Sahn or Bahow: It’s a central open courtyard, rectangular or squared in area. It is an essential element in pious foundations as madrasa and mosque, to supply the entire building with sunlight and fresh air (aeration and ventilation )

43

Fikry, A. “Masajid al-Qahira wa Madaresha”, Mosques and Schools in Cairo, Part II, The Ayyubid Dynasty, Dar al-Ma’aref, Cairo, 1969. Damage based selection of techniques

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Cells: They are the rooms where students and residence stayed at a madrasa and khanqah(44)

Plate (12): Design Principles of Mosque and Madrasa (School) from Early Islamic Period until the Bahrite Mamluk Period [After "Principles of Architectural Design and Urban Planning..", PP. 465-467]

44

Burgoyne , M.H., Op.Cit., p. 63


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Plate (13): Design Principles of Mosque and Madrasa (School) from Bahrite Mamluk until Ottoman's Period. [After "Principles of Architectural Dosing and Urban Planning..", PP. 465-467]


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(3) The Khanqah (Monastery): It was the monastic (sufi) residence for mystic life and study, whose plan consists of a central courtyard (sahn) surrounded by lateral rooms (cells) (45). It’s another type of pious structures, similar in function and planning to the madrasa, but was devoted for “Sufis”, who espoused the mystic-life as an esoteric approach to Islamic religion in which the seclusion and asceticism played important roles(46). Salah al-Din introduced the first khanqah to Egypt during the Ayyubid period, which was established on the premises of a Fatimid palace at the centre of Cairo. Although it had not survived, it was considered as one of the most important khanqah in Cairo during medieval periods. The khanqah (monastery) main function was similar to madrasa, i.e.: to teach the Sunni-rites, and lodge its sheikhs and students. In the early khanqahs, the Sufis led a monastic life according to their own strict regulation and were also sponsored in the same manner as the students of madrasas. The late khanqahs were similar to madrasas and some madrasas played the role of khanqahs to lodge number of Sufis students (47). II) Public and Service Architecture in Islamic Egypt 1- Early Islam (Caliphate)- Umayyads and Abbasids Periods There are no remains of public or service buildings of any historical, archaeological or architectural value that could help us visualize their plan and building techniques and, therefore, determine their design principles. Nevertheless, researchers have quoted historians who state that Moslems, during the Caliphate’ period, had different kinds of public and service buildings such as public baths and hospitals (Maristans). Ibn Duqmaq, for instance, stated that Amr ibn al-'As built a bath named "Rat bath" as the first public bath to be built In Islamic Egypt. It was known by this name because of its small size if compared to the baths built by the Byzantines. The bath was probably made of three basic units as the Roman and Byzantine baths before It, these units were: The cold room, the warm area and the hot area in addition to the (fire house) the remaining unit of the bath. That was similar to the two old examples of baths of the Islamic periods in al-Shim (Syrai): Bath of Qusair ‘Amra 94-97 A.H./712-715 A.D. and al-Sarakh bath 107.111 A.H./725-730 A.D. Both were built after the Rat Bath. The reason for not finding a trace could be attributed to destructive factors that at-Fustat had to undergo. It also became known that muristans were established during the Umayyad period, as ibn Duqmaq stated. According to him, it was originally a house known as ibn Zuhaid House, located in the Qanadil lane in al-Fustat but there were no remains survived, al Maqrisi also stated that during the Abbasid period, during the reign of Caliph al-Mutawakkil ‘Ala Allah, (242 A.H./856 A.D.), al-Fath ibn Khaqan built a maristan in a section of al-Fustat known as al Maghafir district located between the urbanized area of al-Fustat city and the musalla of Khawlan in the Cemetry. This maristan was also demolished, so we failed to visulize their design bases. However, what ibn Duqmaq has stated may denote the effect of muristans’ design - at later periods - on residential buildings in the way of using layouts of the halls, the access to the interior, and separation between quarters of men and women. This architectural concept is noticed in the maristan of Qala’un which was built during the Bahri Mamluk period on the remains of the Fatimid Palace, using one of its halls as a recovery hall(48). 2- The Tulunids Period 45 46 47 48

Williams, C., Op. Cit., p. 23 . Abouseif, D. B.: “Islamic Architecture in Cairo”, Op. Cit., p. 11 . Ibid, pp. 11-12 . Principles of Architecture Design and Urban Planning During Different Islamic Op. Cit, p. 17.


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No trace remains of public or service buildings that may shed any light on their design principles, however, literary sources state that (hospitals) maristans, baths, shopping centres (qaisariyyat) and markets were built during that period. Maqrizi said that Ahmad ibn Tulun has established a maristan in al-Askar in 259-261 A.H./872-874 A.D. and that he spent sixty thousand dinars on its construction, which indicates that the muristan was a large one, and, necessarily, it must have had a system and regulations to organize the reception of patients and their treatment, such as not allowing for the treatment of soldiers or Mamluks. Also, regulations on public health must have been developed and adopted as Maqrizi mentioned two baths in the hospital, one for men and the other for women. The budget for this hospital was collected from endowments (waqfs) made by ibn Tulun from a qaisriyya and a shopping market. The hospital included sections for orthopedics, internal medicine, ophthalmology and others, in addition to a section for tree medical care. Ibn Duqmaq states that this hospital was known as the Higher Maristan, as Kafu al-Ikhshidi had built one in 346 A.H1957 A.D. known as the Lower Mristin. The two Muristans were ruined - as Ibn Duqmaq stated - before the end of the 8 A..H./14 A.D. with no surviving remains(49). 3- The Bahri Mamluks Period During this period several patterns of public buildings and service buildings were known e.g. Wakalas, tenant houses, sabils and maristans. No trace remained of this period that could be studied to help visualize its architectural principles of design except the remains or the muristan of Qala'un - see (Pl. 7). The muristan was operated as a hospital and a medical school as foundation documents referred documents referred to halls for holding scientific seminars for medical study and physicians. The architect followed the introvert pattern onto courtyards, whose sizes differed according to their functions. The principle of separating the two sexes in different quarters was also observed in the plan, which also included wards for surgery, orthopedics, ophthalmology, internal medicine, psychiatry and neurology, a dispensary and pharmacy in addition to quarantines. The muristan also contained teaching halls and a scientific library. The plan provided all necessary services from kitchens, laundries and utilities. The muristan was isolated from the weet to provide a sense of peacefulness and transfinite for the patients(50). 4- The Burgi Mamluk (Circassian) Period The patterns of public buildings have varied during the Burgi (Circassian) Mamluk period, and we will outline herebelow the design principles of some patterns of these buildings: 4-1 The Bimaristan: The ground plan is designed on the basis of achieving the introvert concept and the· provision of privacy by separating the mens' quarters from womens' quarters, each containing clinics for surgery, ophthalmology and internal medicine. Elements of the building are grouped on internal courtyards on which the qa'as open. These consisted of a durqa'a and iwans. The design also included a pharmacy, a library, a praying house, a sabil and a kuttab and shops in some examples, in addition to the necessary services and utilities. An example of a bimaristan of that period is the bimaristan of al-Mu'ayyad (Pl. 14).

49 50

Principles of Architecture Design and Urban Planning During Different Islamic Op. Cit, p. 26. Ibid, p. 160 .


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Plan

The Entrance Internal Façade of the Iwan Plate (14): The Bimaristan of Al-Mu'ayyad The entrance of the bimaristan resembles that of religious buildings in so far as it is placed in an arched recess in the center of which is the entrance door, which has two sitting benches on both sides, topped by two jambs. This is obvious in the entrance of the bimaristan of al-Mu'ayyad. Architectural treatment of the external facades of the building are similar to those of religious buildings in the same period, as geometrical decorations are used and leaf-shaped crenellations topped the building, and facades reflected the space behind it. Limestione is used in construction and vaults, domes and wooden ceilings for covering other spaces. 4-2 The Sabil and Kuttab: Architecture of this period has been distinguished by the grouping of the sabil and kuttab always in one block, sometimes containing a residential part. The buildings of sabils and kuttabs were made separately in a few examples such as the Sabil and kuttab of Qaytbay in Saliba (Pl. 15) or annexed to another building which is the majority, such as the Sabil of Khanqah Farag). Entrances of independent sabils are similar to entrances of religious buildings such as the Sabil of Qaytbay in Saliba. Usually the sabil is placed in the corner of the building, and has two or three windows according to its location with relation to the surrounding streets. On top of the sabil would be the kuttab, with its facade as a wooden balcony with arches, topped by a projecting roof leaning downwards.


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Plan and Elevation NW Façade Plate (15): The Sabil and Kuttab of Qaytbay in Saliba Facades have reflected the internal space formation, and the same elements of decorations and colours common at that time were used, such as leaf-shaped entangled geometrical decorations and vertical rectangular niche with stalactites, or continuous moldings, emblems and tiraz bands, in addition to using the style of red and white, black and white courses alternatively. All this appears clearly in the Sabil of Qaytbay. Stone is used for building the bearing walls inside and outside, while red bricks are used in building the tank and damp areas, while wood is used for ceilings, and marble for encrustation and in the marble plate at the drinking fountain as found in the Sabil of Qaytbay. All materials are natural from the environment and are suitable for the method of construction used and for the climatic conditions, a matter that reflects adaptability to the surrounding environment(51). 4-3 The Wakala and Khan: The ground plan is made so as to achieve the introvert concept around a rectangular open courtyard surrounded by four riwaqs in the ground floor, as well as to provide privacy for the housing units in the upper floors. Thus, the commercial activities, storehouses, and shops in the lower floors are separated; sometimes the plan included a sabil1 and kuttab. Examples of these wakalas and khans are the Wakala of al-Ghuri in al-Azhar (Pl. 16), and Khan al-Zarakisha (Pl. 17). The khan was also named the hotel and the residential. Section was called Rab'e (Tenant House). The housing units consisted of one or two floors, each containing an entrance, service rooms, hall and a sleeping quarter. Mashrabiyyas were used for overlooking on the courtyard or the street, thus maintaining the privacy of the house, in addition to providing sufficient air and light for the housing units. An example of using mashrabiyyas in wakalas and khans is Khan al-Zarakisha(52). The main entrance of the wakala or khan is distinguished for its treatment in a style similar to that of religious buildings as it is designed as an attractive entrance in a recessed high rectangular niche topped by a trefoil arch. Following the entrance would be a vestibule that leads directly to the courtyard and is not followed by a corridor. It is believed that this was to facilitate commercial activates, and thus was not intended as a bent entrance. An example of wakala entrances is that of wakala of al-Ghuri's. The secondary entrance leading to residential quarters are not treated in any special way and are kept away from the main entrance to maintain privacy for the housing units.

51 52

Principles of Architecture Design and Urban Planning During Different Islamic Op. Cit, p. 278. Ibid, p. 279.


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Gr. Plan


The Corte Plate (16): Wakala of al-Ghuri

Gr. Plan

Main Façade

Plate (17): Khan al-Zarakisha The external formation of facades depend on variation of measurements and shapes of the openings and mashrabiyyas, with gradual protrusion sometimes and assurance of horizontality with wooden beams. Surface formation by floral and geometrical decorations and continuous moldings are used, as well as the mushahhar style red and white courses alternatively. An example of facades of the wakalas is that of al-Ghuri's. Facades expressed the activity behind them in a way that it distinguishes between residential and comrnencal quarters also residential areas overlooking the courtyard are distinguished by mashrabiyyas, while the commercial quarters are distinguished by grouping the ground and first floors by pointed arches and arcades on which store rooms open in each of the two floors. This is obvious in the courtyard of wakala of al-Ghuri. If the openings reflect the activity behind them, they do not always indicate the space in there, as sometimes it gave the impression that there were four storeys behind them, whereas they are only two. Limestone is used for building external walls overlooking the street and the courtyard, also in the stairs and vaults used for roofing store rooms. Red bricks are used for building internal partitions especially for services and utilities, while wood is used for roofing housing spaces and for making wooden beams in the facade which served in strengthening the building. Bays are provided with Damage based selection of techniques

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wooden mashrabiyyas, while the internal walls in the residential quarters are covered by plaster. It is found that materials used for construction are natural suitable for methods of construction and adaptable to climatic conditions such as providing the necessary heat insulation. 4-4 The Bath: The analysis shows that the basic elements of which the plan consist are: 1- A main bent entrance and secondary entrances; 2- A dressing room, consisting of a qa'a, a durqa'a and iwans; 3- Cells for resting and getting used to the hot degrees of the bath; 4- Heat house with water basins, surrounded by cells; and 5- A third house that has iwans, cells and baths ending with, some cells. Annexed to the building is the fire house. In addition to the former elements the bath may have been connected to shops or a sabil. The entrances are similar to those of religious buildings, and windows and simple qandaliyyas are used in the formation of external facades. Limestone is used in building walls and red bricks for building the fire house and damp areas; also stalactites are used in the internal formation. An example of baths of this period is al-Mu'ayyad Bath. 5- The Ottomans Period Different types of services and public buildings are found in the Ottoman period being an extension of prevailing public building's in the former periods. Herebelow we present the design principles of some patterns and types of those buildings: (53) 5-1 The Sabil and the Kuttab: From studies anti analysis It is found that there are two patterns for the design and formation of the building, in both patterns the building includes a sabil and a kuttab above in one block. following the Burgi Mamluks design. The main difference between the two patterns is in the external and internal formation and also in the plan pattern. The first pattern follows the Mamluk sabils with some Ottoman influences in the formation. however, the early models of this pattern are constructed in this form due to the proximity of the Mamluk period, such as the Sabll of Khisru Pasha (Pl. 18) and it is believed that the late models constructed according to this pattern, are probably in response to the wish of the founder of the building as in the Sabil of Abd al-Rahman Katkhuda (Pl. 19).

Plans

General View Plate (18): Sabill of Khisru Pasha

53

Principles of Architecture Design and Urban Planning During Different Islamic Op. Cit, p. 387.


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Plan & Main Elevation General View Plate (19): Abd al-Rahman Katkhuda The building includes the sabil and the kuttab in one block, with the sabil situated in the ground floor and its two or three windows overlook the streets in the area covered by a bronze grill. 'The kuttab is located in the upper floor, Its facade is a wooden balcony with arches topped by projecting eaves as seen in the facades of Sabil and Kuttab of Khusrau Pasha. The external facade reflects the Internal space formation, while in the internal formation, elements From Mamluks period as coloured marble in alternative black and white, red and white courses are used; also the wooden ceilings are coloured and decorated by star patterns, as well as using formation elements of the Ottomans period. An obvious example of Internal formation is the Sabil 'Abd al-Rehman Katkhuda. However, the external facades continue to have formation elements Inherited from the Mamluk period such as vertical :rectangular niches and rows of stalactites, and entrances, elements of which are similar to entrances of. Mamluks religious buildings, in addition to the formation of the alternative black and white, red and white· courses. Nevertheless, Ottoman influences are obvious in the ending of the vertical rectangular niche with a segmental arch, not by stalactites or indented surfaces, and using the circular arch for window openings and supporting projected mashrabiyyas of the kuttab on stalactites. Also Ottoman influence appears in fitting the sabil's windows with bronze grills. This Is also obvious in the Sabil of 'Abd al-Raoman Katkhuda. Stone is used in building the outside walls and red bricks for internal walls in the damp areas and the tank, and a damp proof mortar. Also, mabrle is used in the floors -and the dados of walls and columns, coloured ceramic is used in encrustation of walls and wood in the ceilings and the projecting eaves. The second pattern follows the one dominant in the Mamluk period with a sabil and a kuttab, above are connected with another building, such as the Sabil of the Madrasa of Sultan Ma~mijd, and sometimes as a separate building such as Sabil Ruqayya Dudu. However, the elements of formation and the plan are influenced by Ottoman architecture and foreign arts of Baroque and Rococo. The sabil has from three to five windows in the facade for giving water to the thirsty, made of bronze grills decorated with floral ornaments and arched with segmental arches. The facde of the sabil is semi-circular in shape, while the kuttab overlooks the street through an arcade of circular arches supported on marble columns ending by wooden projecting eaves. This appears in both the Sabils of Madrasa of Sultan Mai;imud and the Sabil and Kuttab of Ruqayya Dodu. The internal formation depends on ornaments engraved on stone and coloured Turkish Ceramic and coloured marble floors, while the most distinguishing aspect of the external formation is using Damage based selection of techniques

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circular periphery of the sabil and the kuttab, also in the segmental arches, the coloured ceramic and the bronze grills in all these elements, the Ottoman influence clearly shows in the architectre, in addition to inherited influences' from Mamluks architecture represented in intersecting moldings and floral and geometrical decorations engraved in the stone. An example of this pattern of facades from the Ottomans sabils, is that of Ruqayya Dudo. Stone is used in building walls, wood in making ceramic, mosaic for encur-stations of walls and marble for floors and columns, which are sometimes used as formation elements and not as structural ones. All of these are materials widely used from former period due to their suitability for the climate and the environment. 5-2 The Wakala (Commercial Building): The plan is designed on the basis of the inside design pattern and arrangement of elements and units of the Wakala around an open rectangular courtyard following the former prevailing pattern in the Mamluks architecture for commercial buildings. The wakalas include- - as in the Mamluks period - a residential section in the upper floors and a commercial part in the lower floors taking into consideration privacy for the residential part and separating its entrance from the main entrance of the wakala which is designed as a high inviting entrance. Whereas the entrance of the residential section Is not treated in any special way and comes far from the main entrance. The residential units consist of an entrance, a lavatory, a small kitchen, a qa'a and a sleeping wing. The commerical part in the two first floors consists of shops overlooking the street, and depots in the ground and first floors around the courtyard.

Gr. Plan

The Court

Plate (20): Wakala of Bazar'a The formation of internal and external facade took into account the distinction between the residential part and the commercial one as the ground and first floors are arranged around the courtyard through open circular arch two floors high and by a corridor around the courtyard, while the upper floor windows are covered by mashrabiyyas which provide privacy for the housing units as well as ventilation and light. The external facades, however, are distinguished, in their residential section, by their protrusion from the lower floors on stone consoles in addition to upper floors rnashrabiyyas. Limestone is used in building the bearing walls in the ground and first floors and in floors and vaults, while red bricks are used in building the residential quarters. Vaults are used in roofing depots, while wood is used for roofing the residential section. An example of Ottoman commercial buildings is the Wakala of Bazar'a (Pl. 20). 5-3 The Bath: (al-Hammam) From analysis it is obvious that the main components of the bath are as follows: 1- An entrance in the style of Mamluks public buildings. 2- A dressing hall in the shape of a square durqa'a roofed by a wooden lantern and iwans around the durqa'a. 3- The first part is prepared for sitting, so that the person bathing gets used to the heat before Damage based selection of techniques

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and after taking his bath. 4- Heat house which has a plunge bath and cells, covered by a large dome surrounded by small domes. 5- A fire place and utility.

Plan

Elevation & Section Plate (21): The Bath of Tanballi

The plan is based on inward design pattern to preserve the bath privacy. The internal space formation depends on the variation of heights according to the function of each element and the difference in roofing by domes and vaults, in addition to the colour formation of marble in the floors and the decorations of the ceilings. as well as placing stained glass to provide light and a touch of beauty. Hard limestone is used in building walls, vaults and domes and columns are used in large spaces to carry the ceilings, and wood is used for the lantern and marble in tile works, while walls are covered from inside by a damp proof mortar. An example of baths in the Ottomans period is the Bath of Tanballi (Pl. 21). III) Residential Architecture in Islamic Egypt 1- Early Islam (Caliphate) - Umayyads and Abbasids Periods No trace remains of residential buildings from the Caliphate period to help us visulaize their architectural design but literary sources inform us of a number of houses in al-Fustat which were built during the Caliphate period, and are described as “majestic”. For instance, there was the great House of ‘Abd Allah, son of ‘Amr ibn al’As located near the congregational mosque. It was a large house which, as described by ibn Marwan ibn al-Hakam, was built using the Ka'ba square plan. Opposite to it was the residence of Omar ibn Marwan ibn al-Hakam with the empty space In between called “Bain al-Qasrayn” (between the two palaces). The name was later used during the reign of Caliph al-Mu'izz for the area between the two Fatimid Eastern and Western Palaces, and also during the Mamluk period for the area between the two Palaces of Bashtak and Baysari which was demolished later. Other resedential buildings in al-Fustat during the Caliphate Period according to historians, were “The White House” built for the Umayyad Caliph Marwan ibn alHakam (65 A.H./684 A.D.)., “Gilded House” built by Abd al-’Aziz ibn Marwan and the “Guest House” built by Marwan ibn ‘Abd al-’Aziz. We should not also miss to note that Zuqaq al-Qanadil, mentioned earlier, was named “Ashraf (Nobility) Lane” as it hosted a number of houses of nobilities and high ranking people. 2- The Tulunids Period Damage based selection of techniques

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The most common design of residential architecture during the Tulunid's period, it Is concluded, is the wing consisting of a central iwan with two rooms on the sides, preceded by an ambulatory. This wing is found earlier in Iraq, during the Islamic period, in the Palace of al-Ukhaidir of 160 A.H./777 A.D., also in the houses of Samarra of the period between 221-228, A.H./837-843 A.D. and also in the houses of al-Askar to the north of al-Fustat, which may indicate that the concept of this wing was transferred to al-Fustat from Iraq during the Abbasids’ period, where it was known since the Sassanids. Analysis of the houses in al-Fustat, dating from the third to sixth century, prove that the same design was also used during the Fatimids periods. It is also noticed that it was common for the houses of the Tulunids period to have a main central open yard surrounded by rooms and other elements with-as in some models-secondary yards overlooking services facilities and annexes. The shape of the main central yard varied between rectangular and square, whereas secondary yards had no definite shape. In addition, the analysis also shows that there were two main patterns for the design of the horizontal plan and lb. arrangement of its elements: the first pattern is composed of two main wings, each located at one of the shorter sides of the yard, and traditionally is composed of a central iwan surrounded by two rooms preceded by an ambulatory, whereas the rest at the rooms were located on the two longer sides of the yard: the second pattern has one wing preceded by an ambulatory at one side of the yard, whereas deeper iwans and rooms not preceded by ambulatories are located on the rest of the other sides of yard. The pattern of the four iwans overlooking the yard were found in the Palace of Baden in Assur, dating back to the first century A.D., also at al-Hadar in Iraq (third century A.D.) and in Bisapur (242-272 A.D.), and in the buildings of the Sassanids in Fairuzabad, Sarvistan and Ktesiphon. The pattern was used firstly in the resedential architecture and was later adopted by the religious architecture. Upon analysis of the plan of the Tulunids monuments, it is noted that the design was affected by the irregularity of the land shape common in the old Islamic city, (al.Fustat al.Askar), and the variable widths of its roads, which often meet at right random angles. Nevertheless, the main central yard maintained its regular shape. The overall design was based on ensuring privacy of the house by using the bent entrance, also to the introversion around the central yard and also upon separation of men’s and women’s quarters. It is believed that the ground floor was used as daily living rooms and lot reception of men, where the upper floors were used as bedrooms and lot the household and women. Red bricks was the main building material used during this period, stucco was used for plastering, ornaments and window lattice, whereas wood was used for the construction of ceilings and binders for wafts, (as traces of these binders were found in the walls). Vaults were also used in roofing some of the ground floor rooms. Some remains of the houses Mi al-Fustat contained shops or stores on the exterior whereas others contained service rooms such as stores, stables and servants quarters in the annex. 3- The Fatimids Period The plan that was predominant during the Abbasids and Tulunids continued to be used. The principal elements consisted of a large iwan with two rooms on the sides, and opening onto the Courtyard through a crossing riwaq. During the sixth A.H./l2th A.D. another pattern of q’As appeared, which continued during the successive Islamic periods. The qa'a consisted of a durqa'a with an iwan or durqa’a with two iwans (al-Dardir’s qa'a). Vaults were used for roofing the iwans and wooden lanterns for covering the durqa'a. Cupboards and recesses for sitting were installed in the walls. Stones were used for the construction of bottom parts, while marble was used for floors. The qa’a were connected to a group of side rooms and corridors connecting them to other architectural elements. 4- The Ayyubids Period The design of the qa'a ill the Ayyubid period was a development of the qa'a of al-Fustat and the Tulunid residences, and that of the Fatimids and the Mamluks, as iwans were included in the qa'a, Damage based selection of techniques

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and the central area was covered by a dome. It is probable that the plan of the qa'a which is the principal element in residential buildings at the end of the Fatimids period (al-Dardlr Qa'a) have continued over to the Ayyublds. where Mamluks residential buildings had similar qs'as. The plan of the Ayyubids madrasa was also influenced by the residential qa'as . 5- The Bahri Mamluks Period Islamic principles were taken into consideration in the plan by providing privacy necessary for the residents, which was achieved by openness onto the courtyard, and using the bent entrance which was treated in the same manner as in mosques and madrasas and was articulated by placing it in a high rectangular portal crowned by stalactites similar to what we find in the Palace of Alin Aq-al Husami, and the Palace of Yashbak. The ground floor usually contain the bent entrance, depots, stables and a mill in addition to the servants rooms, the takhtabush, and the reception qa'as as in the Palaces of Alin Aq- al-Husami and Palace of Bashtak (Pl. 22). The upper floors contained qa'as, bedrooms and the utilities. In the design, consideration was given also to separating men from women and making use of the climatic conditions whereas the qa'as were oriented towards northern wind besides using the mashrabiyyas, which in addition to their role in climatic treatment they served to maintain home privacy as found in the Palace of Bashtak and the Oa'a of Muhib alDin. Gradual approach to the exterior 'I! achieved by moving through the rooms to qa'as and finally to the yard. The bent entrance helped ensuring the approach from the external space of the street to the internal space of the house.

Plan

The Durqa'a of Palace Plate (22): Palace of Bashtak

Limestone was used in the ground floors and external facades and in the vaults of the ground floor, while red bricks were used in the upper floors. Wood was used in ceiling and mashrabiyy as. Walls and floors of qa'as were encrusted with marble. All the materials used were natural from the surrounding' environment, providing heat insulation and providing a cooling internal climate. The openings overlooking the outside were few so to ensure privacy and preserve neighbourhood rights. The external facades were formed in a manner to express the space beyond by using and distributing wooden mashrabiyyas, the rectangular windows and grills around the facades. 6- The Burgi Mamluk (Circassian) Period From analysis, it is obvious that the plan and openings for residential buildings are laid on the basis of providing complete privacy for the household and respecting neighborhood rights and the Damage based selection of techniques

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street. This was achieved by the introvert principle and by using 1he bent entrance and mashrabiyyas. The design respected the street line in the ground floor with the protrusion in the upper floors to allow an additional area, and casting shadows on the lower facades and on the street. The house architectural elements are arranged around the courtyard., and the bent entrance is used for entering from the street to the" courtyard, also to reach the living quarters from the court. The ground floor contains the reception qa'as, the sitting area for common people, the storerooms, servants rooms, utilities and services; while the upper floors contain qa'as, living moms, bedrooms services and utilities needed for the household. Consideration was given to separate vertically between services, stores and living quarters; also the horizontal separation between living and residential quarters of the household and living quartars of guests, and special stairs for each are provided. An open sitting loggia is located facing the north in the first floor overlooking the courtyard through pointed-arched arcades. Examples from residential buildings of that pertod are the house of Oaytbay (Pl. 23) and the house of al-Ghuri. Geometrical and floral decorations and triaz bands are used in the internal formation of walls and ceilings. also the variation 'and difference of window openings from one floor to another, as well as the gradation in the spaces from the external space of the street across the bent entrance, the vestibule and the corridor towards the internal space of the courtyard, and from-the space ,of the' room with normal height to the space of the qa'a two storeys high to the sitting loggia open onto the courtyard to the open courtyard. The presence of the courtyard and the pyramidal height of internal spaces helped in increasing air circulation inside the building and ameliorating the internal climate.

Door Detail

Gr. Plan

The Maq'ad from the Court Plate (23): House of Qaytaby

The external facades reflect the internal space behind them. Also, protrusions are used in formation of facades in addition to the colour formation according to the mushahhar style of red and white alternatively, and using natural wooden structural elements. The facades are crowned by leaf-shaped crenellations. Stone is used for building external walls and vaults, while red bricks are used for building internal partitions. damp areas and upper walls, while wood is used for making ceilings and in rnashrabiyyas and horizontal beams in the facade. Also stucco is used for plastering internal walls, and' Damage based selection of techniques

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building materials have expressed the method used for construction and for confirming adaptability to the environment, as well as their suitability for prevailing climatic conditions as they are all used on their natural form . 7- The Ottomans Period It is found that design principles for residential buildings, whether they are large buildings with numerous storeys, inhabited by high ranking people, or small houses for the common, are almost the same and based on the idea of the inward design pattern and separation between men and women. The design of large residential buildings is based on the principle of inward design pattern, since most of the elements of the house are gathered around a square or rectangular internal courtyard from which vertical and horizontal movement is distributed around the different elements and activities. To maintain the sanctity of the house the bent entrance is used, which in turn not only maintains the privacy, but also act as a transition space from the street to that of the courtyard and from the external climate to the internal one, and in addition to the main entrances, secondary entrances are made to be used by the household. Ascending stairs from the courtyard to the upper floors are numerous and their locations vary, and not all the stairs continues upward as each one ends in a different floor, also stair cases are located between the floors and do not reach the courtyard, in order to provide privacy for the household. Usually. the ground floor contains, in addition to the ground qa'a, the takhtabaush, the bent entrance and the stair cases to the upper floors, rooms for servants, utilities, depots and a mill and water wheel, while the upper floors contain qa'as, sleeping closets, living rooms and services. Also the qa'as are annexed by secondary rooms and services. Also the qa'as are annexed by secondary rooms to achieve their independence from the' rest of the house, and in the first floor there is usually a sitting loggia that open on the courtyard. It is observed from analysis that the design has taken into account the vertical separation between services in the ground floor and living and sleeping quarters in the upper floors, as well as separating - vertically and horizontally between the wing of the household (Haramlik) and living quarters for guests and men (Salamlik). Example of residential buildings of that period are the House of Kiridliyya and House of Amna bint Salim and house of Gamal El-Din El-Dahabi (Pl. 24) and House of al-Suhaimy (Pl. 25). The design has taken into consideration the prevailing climatic conditions and winds movement in directing the house units and the loggia is directed to the north and north-west. Openings are not as many in the west and south-west sides, and the mashrabiyyas are made in a way to allow ventilation and light as well as breaking the intensity of sun rays, and casting shadows on lower floors.


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Plan Elevation & Section Plate (24): House of Gamal El-Din El-Dahbi In the internal formation, the architect depends on the variation and gradation in internal heights, using niches, small iwans, closets and shelves in walls as well as coloured geometrical and floral decorations in the ceilings, and coloured ceramic in the walls, in addition to coloured ceramic in the floors. The formation of internal facade depends upon variation of turnery wood forms in the mashrabiyyas and on stained glass stucco lattice and on the difference. in size and projection of the mashrabiyyas. The architect also gives attention to the internal formation individual facade more than that given to the external formation - community's facade - which is marked for simplicity as it depends on the variation of sizes and shapes of openings and mashrabiyyas and the difference in its projections and the variety in designing the turnery wood units for each mashrabiyyas, as well as using projections in the upper floors, which helps in casting shade on the 'lower floors and in increasing areas of the upper floors. Examples of facades of residential buildings in the Ottoman period are facades of the House of Amna bint Salim, and facades of alKiridliyya house.

One Mashrabiya in the house

Plan and Section A wind catcher Plate (25): House of al-Suhaimy Stone is used in building the ground floor, while the upper floors and internal walls are built of red bricks, and double walls are used in different areas of the building. It is noticed that stone was left on its natural form, while red bricks are covered by stucco plaster, and wood is used in making ceilings and lanterns, and in making wind catchers and mashrabiyyas. Marble is used for encrustation of floors, dados, and suffas. The materials used are the same that were commonly used during former periods and they are all suitable for the climatic conditions. Damage based selection of techniques

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The small residential houses built by the common people are numerous in style and flexible in design, which usually adopts the inwards pattern, since the element's of the house are arranged around an open courtyard. The ground floor contains a reception hall or sitting loggia to receive guests, and depots, a stable and a mill, whereas the upper floors (one or two) are assigned for members of the family and contains bedrooms and living rooms. Stone is used in building the lower floors, while red bricks are used in building the upper floors, and are covered by stucco plaster. VI) Fortification Architecture in Islamic Egypt 1- The Fatimids Period When Gawhar al-Saqilly founded Cairo, It was surrounded by walls of mud bricks and gates. When Badr al-Gamalli made his expansions on Cairo and rebuilt its walls, he constructed the great fortification gates (al-Nasr, al-Futuh and Zuwayla). The plans of these gates (Pl. 26) had variable designs by using square and semicircular towers; each gate is composed of two squares, or semicircular towers with the entrance door in between topped by several different successive arches adding to the strength of the buildings. The soldiers rooms are placed on top of the towers, supplied with openings and arrow slits, while the bottom parts of the towers are massive structures.

Plan

General View Plate (26): Bab Zuwayla

To increase the fortification capacity of the gates, the walls are constructed using rounded columns set horizontally. The formation includes arches lintels and shallow rectangular niches with simple decorations. The distribution of openings and arrow slits and crestings around the formation, in addition to stones, give the building a strong sense of solidity. The design of the gates is based on the relations between the square, circle and golden rectangle. Their construction is distinguished for its originality as it building materials are brought from the surrounding environment, It is believed that utilizing stones brought from older buildings is due to the desire to save on construction costs.

2- The Ayyubids Period Al-Gabal Citadel represents the most distinguished works of fortification of the Ayyubids. It Is formed of a number of towers connected by- walls in-between. The forms and types of its towers varied in their plan, facades or the type of stone used. Three types of towers were found in the Damage based selection of techniques

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Citadel; the first was semi-circular towers which are either single or double enclosing between them a wall or an entrance, and composed of two similar storeys, each in the form of a square hall with arrow slits; the second type were the circular corner towers similar to the first kind and the third type are rectangular or square towers of three storeys, the two bottom ones are in the shape of a square hall with arrow slits in its walls, while the third storey is the roof of the tower which is also topped by a parapet and arrow slits (Pl. 27). Originality is expressed in the method and the use of building materials, which were brought from the environment in their natural forms, either polished or rusticated and in the shape that produced roughness in expression to stress the Citadel's function, which was either to counterattack the invaders or to keep control over Cairo. During the Ayyubid period the walls of Cairo were extended to include .Cairo, al-'Askar, al-Oata'i, and al-Fustat. The walls were reinforced by a number of towers which resembled those of the Citadel and gates that had no towers - in the form of an arched door followed by a vault or a vestibule similar to Bab al-Carafa, and these doors were used as entrances to Cairo in addition to its fortifying function.

General View from Salah El-Din Square

Plan


General View from Salah Salem St. Plate (27): Al-Gabal Citadel

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3- The Ottomans Period: Concerning the fortification buildings, nothing valuable has remained from the Ottoman period in Cairo from which we may study their design principles, except the citadel of Muhammad 'Ali in al-Muqattam hills. Nothing more than some additions, renovations or maintenance in the citadel of Salah al-Din is made by his former Ottoman rulers. This building is characterized by its small size and the clear geometrical shape of. its corners which enables one to control all directions. The presence of a great number of fortification openings, and the great thickness of the walls may have helped defenders in using it as bridges for movement, as well as the existence of a trench in front the citadel's gate to protect it. In the middle of the south-east facade there is a tower that assists in sight-seeing and defense. Stone is used in construction. In the center of the citadel's court there is a water tank and soldiers barracks built of bricks. It is noticed that some features of European architecture of that period are used in the Citadel, among which are the curved lines on top of the entrance.


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REFERENCES GREEK-ROMAN ARCHITECTURE IN EGYPT 1). David. D. Zink. The Ancient Stones Speak. 1979. Musson Book Co. 2). Cesar Paternosto. The Stone and the Thread. 1989. University of Texas Press. 3). G. Hancock. Heaven's Mirror. 1998. Michael Joseph Publ. 4). J. N .Lockyer. The Dawn of Astronomy. 1964, M.I.T. Press. 5). http://www.geopolymer.org/archaeology 6). A. Service & J. Bradbery. Megaliths and their Mysteries. 1979. Macmillan. 7). D. Trump and D. Cilia. Malta: Prehistory and Temples. 2004. Midsea Books. 8). Petrie as quoted by Smyth, Our inheritance in the Great Pyramid, 1890 Ed, pp20. 9). http://www.ancientcyprus.ac.uk/papers/iriawreck/pulak1.asp 10). Kalb, Philine, Megalith-building, stone transport and territorial markers; evidence from Vale de Rodrigo, Evora, south Portugal. Antiquity. Sept 1, 1996. 11). C. Morton and C. L. Thomas. The Mystery of the Crystal Skulls. 1997. Thornson's. 12). http://www.ucd.ie/archaeology/research/phd/killian_driscoll/ 13). Reynolds, Ffion. Time and mind. Volume 2, Number 2, July 2009, pp. 153-166(14). 14). http://thehobgoblin.blogspot.com/2009/11/new-stonehenge-bluestone-mystery.html 15) Coulton, J. J. Greek Architects at Work. London: Elek Books Ltd., 1977. 16) Lawrence, A. W. Greek Architecture. 5th ed. New York: Yale UP, Pelican history of art, 1996. 17) Sadler, Simon. "Lecture 3." AHI025. ART 217. 14 Apr. 2008. 18) Tomlinson, Richard A. From Mycenae to Constantinople: The Evolution of the Ancient City. New York: Routledge, 1992.

GREEK-ROMAN MATERIALS

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Arnold D, “Temples of last pharaoh”.1999. New York, Oxford unive press. Baikie J. “Egyptian antiquities in the Nile valley”.1973. London. Baines J., Malek J.“Atlas of Ancient Egypt.”.1980. Les Livres De France, None Stated. Bard K.A., Blake S. “Encyclopedia of the archaeology of ancient Egypt”1999. New York. Empereur J. “A short guide to the Catacombs”.1987. British museum press. Empereur J. “Alexandria Rediscovered”.1998. British Museum Press, ISBN 0-7141-1921-0. Freeman C. “Egypt, Greece and Rome (Civilizations of the Ancient Mediterranean)”.1996. Oxford University Press, ISBN 0 – 19 – 815003 - 2. Hemeda S., Pitilakis K., Papayianni I., Bandis S., Gamal M. “Underground monuments (Catacombs) in Alexandria, Egypt”.2007. Proceedings of the fourth International Conference on Earthquake Geotechnical Engineering, Thessaloniki, Greece, 25-28 June. Hemeda S., Pitilakis K., Bandis S “Geotechnical investigation and seismic response analysis of underground tombs in Mustafa Kamil Necropolis in Alexandria, Egypt”.2008. Proceedings of the first International Conference on Giza through Ages, Studies in Monuments, Restoration, Environment and Tourism, Giza, Egypt, 4-6 March. Hemeda, S. An integrated approach for the pathology assessment and protection of underground monuments in seismic regions. Application on some Greek-Roman monuments in Alexandria, Egypt. 2008. Ph D thesis, Aristotle University of Thessaloniki, Greece. Redford D B. “The Oxford Encyclopedia of Ancient Egypt”2001. The American University in Cairo Press, ISBN 977 424 581. Damage based selection of techniques

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Shaw I; Nicholson P. “The Dictionary of Ancient Egypt”.1995. Harry N. Abrams, Inc., Publishers ISBN 0-8109-3225-3. Theodore V. “Alexandria, City of the Western Mind”.2001 Free Press, ISBN 0-7432-0569-3. Wilkinson R. “The Complete Temples of Ancient Egypt”.2000. Thames and Hudson, Ltd, ISBN 0500-05100-3.


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6 PARTNER N° 18 - MONU 6.1

USING ADVANCED COMPOSITES TO RETROFIT LISBON’S OLD “SEISMIC RESISTANT” TIMBER FRAMED BUILDINGS


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REHABILITATION OF LISBON’S OLD “SEISMICRESISTANT” TIMBER FRAMED BUILDINGS USING INNOVATE TECHNIQUES


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CAP- VI - COMCEPÇÃO E PROJECTO DAS INTERVENÇÕES DE REABILITAÇÃO ESTRUTURAL” AND “CAP. X – ANÁLISE ESTRUTURAL E VERIFICAÇÃO DE SEGURANÇA” IN «REABILITAÇAO ESTRUCTURAL DE EDIFICIOS ANTIGUOS»,GECORPA


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6.4


“SISMO 1998 - AÇORES - UMA DÉCADA DEPOIS” - EDIÇAO C. SAUSA OLIVEIRA, ANÍBAL COSTA, JOÃO C. NUNES, 2008


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7 PARTNER N° 7 – UPC 7.1

STRUCTURAL FEATURES AND COLLAPSE MECHANISMS OF HOUSES AND CHURCHES. TYPICAL URBAN BUILDINGS AND GOTHIC CHURCHES IN BARCELONA

1 INTRODUCTION This study aims to discuss the mechanisms of building collapse due to earthquake for different types of buildings existing in the city of Barcelona. The case of Barcelona is presented as an example of a location subjected to only moderate seismic risk. In spite of this moderate risk, and due to the lack of memory on past earthquakes and concern during recent times, a large amount of buildings have been constructing showing very limited and even insufficient seismic capacity even for the moderate earthquakes expected. The main characteristics of these buildings are here described and some possible collapsing mechanisms are considered. Two different types of buildings are discussed in the present annex. Firstly, typical buildings belonging to the classical construction period of the “Eixample” (enlargement) are described and analyzed. This construction period includes some 80 years beginning around 1860 and reaching until the end of the Spanish Civil War in 1939. The “Eixample” covers a very significant part of the today’s urban texture of Barcelona. Some information regarding the construction system of L’Eixample is taken from Paricio (2009). Second, a set of religious buildings is also described and analyzed regarding expected collapse mechanisms. These buildings include a set of important Gothic churches located in the ancient quarters of Barcelona. These building are characterized by their significant height, large spans and limited buttressing. In fact, is known that some of these buildings already experienced some damage during the earthquake series which affected Catalonia during the 14th and 15th centuries.

1 TYPICAL BUILDINGS OF THE “EIXAMPLE” OF BARCELONA 1.1 Origin and development of l’Eixample In the mid-nineteenth century, Barcelona was a small and completely walled perimeter wall prevented its growth in all aspects. During that time, Barcelona hectares (approximately) surrounded by a free open space of 2.000 hectares. problems caused by a very high urban density, it was decided to spread out across the surrounding space.

city. The existing was a city of 190 Due to the health the urban texture

Through a competition-tender, the Civil Engineer Idelfons Cerdà designed the exitended urban net of the city. Cerdàs’ design, in its beginning, suffered major modifications due to the pressure caused by the population’s density. With the Eixample, it was intended to link all the surrounding towns around the walled city of Barcelona by a street grid net oriented parallel to the sea (Figs. 111). This new grid created an urban complex with an interval between street axis of 113.30 m, oriented 45º North. Most of the urban complex has a square shape except on the block corners, which are cut to form 20 m long chamfered street corners. The width of the streets is at least of 20 m. Damage based selection of techniques

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Figure 1 - Current view of Barcelona´s Eixample.

Figure 2 - Current urbanism of lÉixample. Distribution of typical blocs.


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Figure 3 –Typical inner Courtyard.

Figure 4. Street façade showing typical buildings (Gran Via de les Corts Catalanes).

Figure 5. Street façade (Pau Claris street).


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Figure 6. Street façade (Diputació Street)

Figure 7. Street façade (Roger de Lluria street)

Figure 8. Street façade (corner between Diputació street with Pau Claris street)


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Figure 9. Street façade (corner between Gran Via Street with Roger de Lluria Street)

Figure 10. Street façades (corner of Pau Clarís street with Gran Via)

Figure 11. Street façades (corner between Roger de Lluria street with Diputació Street) 1.2 Architecture of l’Eixample Throughout the period during which lÉixample was built, the architecture implanted was developed according to three architectural styles: Pre-Modernism, Modernism and PostModernism. Pre-modernism Pre-modernism refers to the first construction period of lÉixample and begins around the year 1860 and ends approximately in 1900. Actually, it includes, approximately 45% of the buildings. The architecture of this style is very austere and classicist, with buildings of three floors high and quite plane façades. The façade wall was normally painted or rendered with lime plaster. This time is subdivided in two subperiods: The first period, expanding from 1860 until 1890, the architecture is characterized by a neoclassical style. The height between floors decreases as the floors rise. The second period, from 1890 to 1900, is characterized by its eclecticism. It is worth noting that in Damage based selection of techniques

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the ground floor they introduce cast iron pillars, allowing much larger dimension openings. Also, metallic windowed balconies appear for first time. Modernism Modernism refers to the second period of construction of l’Eixample. It begins around 1888 and reaches until 1915. It includes, approximately, 13% of the buildings of l’Eixample. This period, designed mostly by the first generation of architects who graduated from the University of Barcelona, is characterized by its more free forms, leaving aside the austerity of the architecture of the first period. During this time, large importance is given to the “principal” story, which is designed with additional height and external volume. The balconies turn to a structure of iron beams, and the windowed balconies are made of stone. Post-modernism Post-modernism constitutes the last period and it falls between 1910 and 1939 (until the end of the Spanish Civil War). Nowadays, this period includes, approximately 20% of the buildings. This period is characterized by a return to the austerity of the first ones, as well as to the simplification of the shapes. The mansards are clad in slate, as well as the pent-house apartments which are recoiled from the vertical side of the façade. After the end of the Spanish Civil War (in 1939), reinforced concrete is gradually introduced in the construction of buildings. 1.3 The Eixample’s typical building and materials The typical building from the Eixample consists of a masonry load bearing wall structure with. In most cases, the load bearing walls are in the façades and parallel inner walls. The façades are 11 to 14 m long, allowing for two flats per story. The load bearing walls are complemented with secondary perpendicular walls to grant stability. Unfortunately, these secondary walls were not always built, leaving its role to the thinner partition walls. In some cases, the interlocking between the load bearing walls and the secondary ones has been damaged or has been lost even due to cracking caused by soil settlements. Generally, the load bearing walls of the façades are about 28-30 cm thick, while the inner load bearing walls or the secondary ones are only about 14-15 cm thick. There are to different types of buildings. The first one is the chafer building, at the corners of the square blocks, while the second is the typical joint ownership house placed along the sides of the blocks. The cross-sections highlight four typologies, including buildings built above ground level, buildings with basement, buildings with a basement just under the ground level and buildings with a semibasement. To characterize the earthquake collapse mechanisms, it is necessary to understand how the structure works as a supporting element of the whole building. One must also understand how the wall systems are articulated and how these create a system of “enclosed space”. The load bearing walls are built of bricks set in lime mortar and plastered also with lime mortar. Remarkably, a criterion in the specification sheets of the time indicated that once a existing building was demolished, all those materials that might be usable were left for the builder. Therefore, many current elements of these buildings came from other constructions, leading to a first process of sustainable construction Damage based selection of techniques

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Ceramic bricks are the most widely used material. This material is used for the bearing walls, stairs, floors, ceramic filler blocks, partitions and roofs. The Eixample model is built with more or less standardized brick masonry. Some dimensions vary according to the construction period of the building. During this period the standardized brick or unit is characterized geometrically module by a module of 30x15 cm. The following brick types can are used: Solid Brick 

Regular Brick

30x15x5 cm



Medium Brick

30x15x3 cm



“Picholín”

28x10x4 cm

Hollow Brick 

6 Holes

30x15x10 cm



9 Holes

30x15x11 cm

The most used natural stone is the local sandstone from the Montjuïc Hill. Sometimes, stone from Murcia‘s region, at the South-East of Spain, was also used. The stone is worked in two different ways. First, rubble masonry stone was used in foundations, or for partition walls up to three meters high. If the building was an important one, all the building façade was made of block stone masonry. In some cases, stone works are only found in the Ground Floor, the baseboard of the main façade, or in the perimeter of the openings. Over time, some elements were replaced with artificial stone. Wood is widely used. Local wood was used, specifically Pinus Sylvestris (from Catalonia), Pinus Pinnea and Pine from the Pyrenees. This material can be found both in structural (particularly, to produce the the floor slabs) and non-structural elements. Most commonly, lime mortar was used. Three different types of lime mortar were used: 

Aerial Lime Mortar: Also called “Ordinary Mortar”. Usually included one part of lime and two parts of sand, although the proportion could vary. It was used in brick masonry, foundations and masonry.



Hydraulic Lime Mortar: This was a better quality mortar, but less used. It was produced as a mixture of lime powder and sand. This mortar was used, as the Aerial Morter, in brick masonry, foundations and masonry.



Slow Cement Mortar: This was one of the less used mortars because of its high cost and low resistance. It had a dosage of 1:3.



Portland Cement Mortar: This mortar has a high resistance compared with the previous mortars. It was used in the brick masonry rows that were placed just under the framework support beams. This technique was utilized when no tie beams were used. This mortar had a dosage varying between 1:3 and 1:4.



Mix or “Bastard” Mortar: It consists of a mixture of lime and cement, leading to a final product with the workability of the lime mortar and the resistance of the cement one. Starting in the 20’s, this kind of mortar was first used for brick masonry. The most common dosage in this mortar is 1:0.25:5, meaning that it composed of a portion of aerial lime, a quarter of cement, and five portions of sand.

Starting in 1910, other binders such as Portland cement were used as well.


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According to studies by Joan Bergós (see Paricio,2009) the following resistances were attained (table 1): Table 1 – Compressive strength of used binders

MORTARS

RESISTANCES

Fat lime (high calcium lime)

4,0 N/mm2

Feebly hydraulic lime

1,0 N/mm2

Very hydraulic lime

1,8 N/mm2

“Slow” cement

1,6 N/mm2

Portland cement

29 N/mm2

The following types of masonry are found: (1) Stone rubble masonry was used for the construction of the elements placed in the basement, such as the foundation of walls and pillars, and basement walls. It was also used, in some cases, for divisor walls up a heigh of t3 m. (2) Stone block masonry was used for the main façade of the building. The stone was worked and sculpted in its external faces. Brick masonry was the most commonly used technique, being utilized for load bearing walls, staircases and most of the elements located above ground.

1.4 Geometric features The ground floor it is formed, depending the period of construction, both by a net of walls that are supported on a continuous foundation, or by a perimetral wall system. In the centre there is an arcade system of cast-iron pillars. As mentioned, the façades are normally behave as load bearing walls. The front façade looks onto the street, and the rear façade looks onto the inner courtyard of the squared block. In the interior of the building there are longitudinal and transversal walls, the later, parallel to the façades, acting as well as load bearing walls. The distance between the load bearing walls (and hence the span of the floor slabs) is typically equal or lesser than 4 m. The central core of the floor consists on the staircase and the inner courtyard, limited in turn by 15 cm thick walls. This interior box contributes to stabilize the entire building.


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Figure 12 – Typical floor plans indicating the position of the interior box containing the staircases

Figure 13 – Typical distribution of walls in plan


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1.5 Structural weaknesses The buildings of the Eixample show some problems defects which may affect their overall strength and seismic performance. 

Frequently, the adjoining properties share the same dividing wall.



For many years, and due to an urban density problem, many buildings experienced additions of new floors, causing overload in the building’s structure, and the setback of the upper part of the building.



In more recent times, the inner cores of buildings have suffered several changes at the ground floor level, such as openings at the walls. These changes often waken the structure.



The buildings, and specially those built along the second period, have a significant amount of external ornamentation. Many ornaments are not anchored to the structure and may fail in the case of a seismic movement.



In some cases, an interlocked connection may not have been formed between the bearing walls and the secondary perpendicular walls. Initially adequate connections may have been lost due to cracking caused by differential soil settlements and other actions.



The Ground Floors are weak points with regard to the seismic action, because these levels, intended to be used as commercial spaces, are more diaphanous. Often, the vertical structure at these levels consists of cast iron pillars. The pillars support a grid of iron or steel beams on which the upper load bearing walls are supported. Hence, the strength and stiffness of the inner walls is interrupted or compromised because they do not reach the foundation, but are only supported on a set of pillars.

Figure 14 - Geometric features of two different building typologies. Damage based selection of techniques

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1.6 Collapsing mechanisms Several possible collapsing mechanisms are presented by means of a set of drawings. The presented mechanisms offer a selection of likely mechanisms affecting the exterior façade, but do not constitute a comprehensive list of all possible modes of failure (figure16).

Local failure of balconies and ornaments

Fig. 16 -Collapsing mechanisms for the typical “Eixample” masonry buildings


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Overturning of the front façade walls

Failure of the ground floor structure due to overturning of pillars, especially in ground floors designed for commercial uses.

Fig. 16 -Collapsing mechanisms for the typical “Eixample” masonry buildings (continuation)


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Vertical strip overturning

Fig. 16 –Collapsing mechanisms for the typical “Eixample” masonry buildings (continuation)


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Vertical strip overturning Fig. 16 -Collapsing mechanisms for the typical “Eixample” masonry buildings (continuation)


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Overturning of façade with lateral wall

Fig. 16 -Collapsing mechanisms for the typical “Eixample” masonry buildings (continuation)

Overturning of coner


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Upper façade wall failure

Fig. 16 -Collapsing mechanisms for the typical “Eixample” masonry buildings


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2 RELIGIOUS BUILDINGS. GOTHIC CHURCHES IN BARCELONA 2.1 Description of the buildings Gothic churches and cathedrals built in Catalonia and Mallorca during the 14th and 15th c. are characterized by large spans, transparency between central and lateral naves and other architectural features all contributing to enhance the sense of immensity and uniqueness of interior space (Fig. 1). In three nave buildings, as in the Cathedrals of Barcelona and Mallorca and the church of Santa Maria del Mar in Barcelona, the wish for transparency led to the construction of extremely slender piers. In single nave buildings, the interior spaciousness is achieved by large transverse spans, which amount to a record of 23 m in Girona cathedral. These buildings are located in moderately seismic zones characterized by peak ground accelerations between 0.04g and 0.08g for a 475-year return period according to the EuropeanMediterranean Seismic Hazard Map of the European Seismological Commission (Jimenez et al., 2001) and only 0.04g according to the Spanish seismic code NCSE-02. In spite of being built in moderate seismic locations, the buildings show some interesting structural features which contribute satisfactorily to improve their seismic capacity, such as transverse diaphragmatic arches, thick lateral closure walls adequately interlocked to the rest of the structure, large façade buttresses, and other. The study concentrates in two of the most relevant Gothic churches built in the city of Barcelona, namely the basilica of Santa Maria del Mar and the church of Santa Maria del Pi. These two churches have been chosen because its architectural importance, together with the fact that they actually show damage possibly connected with past earthquakes.

Fig. 17. Interior of Santa Maria del Mar


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Fig. 18 – Interior and façade of Santa Maria del Pi 2.2 Construction features Santa Maria del Mar is a rare case of a Gothic church entirely built during a short period of only 53 years. Moreover, the building has not experienced any significant architectural alteration after its construction, resulting in large uniformity and architectural purity. The structure shows three naves Damage based selection of techniques

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arranged according to a basilical plan. The building includes a set of distinct features, such as large square central vaults spanning 13.5 m and lateral vaults almost as high (but not so high) as the central ones. The vaults, 32 m high, are sustained on octagonal piers with circumscribed diameter of 1.6 m. The church of S. Maria del Pi was built between 1319 and 1391. Its pure Gothic style is evident in the single, 16.8 m span nave, almost devoid of ornaments. The middle of the main façade boasts a large rose window of 10 meters in diameter. Very little is known about the level of awareness of original Catalan builders on the seismic hazard and the intentional inclusion of anti-seismic features in these buildings. Some researchers (Cassinello, 2005) defend that some features as, in particular, the diaphragmatic transverse arches were intentionally built to improve the seismic capacity. Cassinello bases this idea in the correlation existing between the location of cathedrals provided with diaphragmatic arches and the distribution of seismic hazard in Spain. However, these features may also be preferred for constructive of functional purposes. For instance, recent historical research has shown that diaphragmatic arches in Santa Maria del Mar were used to sustain a provisory timber roof allowing full liturgical use of the building while the vaults had not yet been built (Vendrell, 2008). Similarly, the upper flying arches of Mallorca contribute to increase the seismic capacity of the building (Salas, 2002, Clemente 2007) in spite of not having any other clear structural purpose (as the building has never had a high pitch roof). However, their main role as channels to drain rain water is very obvious is one looks to the original architectural arrangements and details of the roof level. Some awareness on the seismic hazards may have existed, as can be drawn from some few historical records. In relation to the construction of the unique nave of Girona Cathedral, some experts of the time, invited by the Chapter in the year 1416, agreed to consider that the construction of a cross-vault with a span of more than 23 m was possible and appropriate; they agreed to validate the capacity of the existing walls and foundations to receive the weight and the lateral thrust of the large vaults of the unique nave. However, some of the experts pointed out that the stability might not be granted in the event of earthquake or hurricane wind (Castro 1996). Whatever the case, these buildings do have some distinct features, as the diaphragmatic transverse arches, the structural and rather thick solid perimeter walls (including only small windows or oculi) and the use of light vault filling, which contribute to increase their seismic capacity. These features are in fact connected to the local construction tradition and show some atavistic link to Roman or Romanesque construction. Conversely, the more modern developments, oriented to produce the diaphanous inner space (slender piers, large spans), add some weakness to the building. 2.3 Hints on past seismic performance The history of earthquakes in Catalonia since 14th c. century has been very much investigated based on abundant historical records (Fontseré, 1971, Oliveira et al. 2006). Seismic activity was particularly intense during 14th and 15th, with significant earthquakes occurring during the construction of Santa Maria del Mar and Santa Maria del Pi themselves. Important earthquakes occurred during years 1373, 1410, 1427, 1428, 1435, 1448, 1511, and later during the 17th c., with epicentre most often located by the Pyrenees. The 1373 earthquake is remarkable for written testimony of the collapse of the upper part of one of the façade clock-towers of Santa Maria del Mar (later reconstructed). According to some historical Damage based selection of techniques

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sources, on Monday February 2, 1428, at about 8 am, a frightening earthquake occurred, of long duration, causing collapse of walls and stairs in the city. In the church of Santa Maria del Mar, part of the “O” [the rose window] collapsed and 21 or 22 people died including man, women and children (Oliveira et al., 2006). Later in 1605, another earthquake is said to have damaged the building. In spite of the very local collapses mentioned, it can be said that the structure of Santa Maria del Mar has withstood successfully severe historical earthquakes attaining in Barcelona an intensity of VI-VII in the EMS-98 scale, according to modern estimations (Oliveira et al, 2006). Since no major restoration has been undertaken in the past, most of the damage visible today, consisting of distinct cracks in walls and façade, might still be the one caused by the past earthquakes. In this case, case, the response of the building to earthquakes of such intensity would be still fully readable today in the shape of rather slight or moderate damage. Less specific information is available on historical effects due to earthquake on Santa Maria del Pi. Some documents indicate that the church experienced severe (but unspecific) damage due to the mentioned earthquake of 1428. Later destruction experienced during and after the Succession War (1701-1714) and the Spanish Civil War (1936-1939), followed by reconstruction and repair, make it difficult today to distinguish the effects of past earthquakes.

2.4 Forseen collapsing mechanism and relatioship with existing damage The most likely failure mechanisms that may occur can be categorized as the following; Overturning of the facade Overturning/ collapse of the upper part of the facade Triumphal Arch Bell tower Overturning of the upper part of the tower These mechanisms can in fact be connected with some existing damage. The observed damage includes the following aspects: existing cracks on the connections between the frontal and lateral façades, vertical or inclined cracks on the main façades and vertical or inclined cracks in the lateral ones. These mechanisms are presented in the following figures. Pictures showing damage possibly connected to their incipient activation are also shown. The foreseen collapsing mechanisms are first presented for Santa Maria del Mar (Figs. 19-35) and then for Santa Maria del Pi (Figs. 36-47).

COLLPASING MECHANISMS FOR SANTA MARIA DEL MAR CHURCH

Overturning of the Main Facade


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Figure 19 – Damage on the front façade


Figure 20 – Crack pattern on the front façade

Figure 21 – Collapse mechanism. Overturning of the façade

Overturning of the Upper Part of the Main Facade


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Figure 22 – Damage around the rose window. Reconstructed wall over the rose window

Figure 24 – Overturning of the upper part of the façade



Figure 23 – Crack pattern on the upper part of the façade

Figure 25 – Collapse of the upper part of the Main Façade

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Separation of the bell tower

Figure 26 – Damaged part on the front façade

Figure 27 – Crack pattern close to the bell tower

Figure 28 – Separation and overturning of the bell tower


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Out-of Plane Deformation / Collapse of the Upper Part of the Bell Tower

Figure 29 – Upper part of the tower

Figure 30 – Collapse mechanism

Figure 31 – Overturning and rotation of the upper part of the bell tower


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Figure 32– Rotation and overturning of the upper part of the bell tower

Figure 33 –Rotation and overturning of the upper part of the bell tower


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Figure 34 – Alternative in-plane collapse mechanisms for the typical nave bay


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SANTA MARIA DEL MAR

Case

Local Collapse Mechanism

1

Overall overturning of the main façade

2

Overturning of the upper part of the main Façade

3

Separation and overturning of the bell tower

4

Collapse of the upper part of the bell tower

5

Collapse of the upper part of the façade

Table 35 – Summary of collapse mechanisms


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COLLAPSE MECHANISMS FOR SANTA MARIA DEL MAR CHURCH

Overturning of the Main Facade

Figure 37 – The extending Figure 36 – view of the cracked crack on the side façade region of the lateral façade

Figure 38 – Overall overturning of the façade

Overturning of the Upper Part of the Main Facade Damage based selection of techniques

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Figure 39 – The cracks on the rose window


Figure 40 – Crack pattern of the area of the rose window

Figure 41 – Overturning of the Upper Part of the Main Façade


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Partial Overturning of the Main Facade

Figure 42 – Cracked region close to the rose window

Figure 43 – Crack pattern close to the rose window

Figure 44 –Partial overturning of the Main Façade


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Figure 45– Overturning of buttresses in the apse


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Figure 46 – Alternative collapse mechanisms of the typical bay


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SANTA MARIA DEL PI Case

Local Collapse Mechanism

1

Global overturning of the façade

2

Overturning of the upper part of the main façade

3

Partial overturning of the main Façade

5

Typical bay

6

Out-of Plane Deformation / Overturning of the Buttresses on the Apse


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Table 47 – Summary of collapse mechanisms for Santa Maria del Pi REFERENCES Cassinello, P. (2005) Influence of historical earthquakes in the construction of Spanish Gothic cathedrals (in Spanish). Annali di Architettura, 2005/17. www.cisapalladio.org Castro, A. (1996) History of Medieval Construction. Contributions (in Spanish). Quaderns d’Arquitectes N. 15, Edicions UPC, Barcelona. Fontseré, E. (1971). Recopilation of seismical information in the Catalan territory between 1100 and 1906 (in Catalan). Generalitat de Catalunya, Barcelona . Jimenez, M., J., Giardini, D., Grünthak, G. & SESAME Working Group (2001) Unified seismic hazard modelling throughout the Mediterranean región. Bolletino di Geofisica Teorica ed Applicata Vol. 43, N. 1-2.See also http://wija.ija.csic.es/gt/earthquakes/ Comisión Permanente de Normas Sismoresistentes (2002). Norma de Construcción Sismoresistente NCSE-02. Ministerio de Fomento, Madrid. Oliveira, C., Redondo E., Lambert, J., Riera Melis, A., Roca, A. (2006) The earthquakes of 14th and 15th c. in Catalonia (in Catalan). Institut Geogràfic de Catalunya, Barcelona. Paricio, A. (2009) Secrets of a construction system. The Eixample (in Catalan) Edicions UPC, Barcelona. Salas, A. (2002) Study of the type bays of Mallorca Cathedral (in Spanish). End-of-study dissertation. Universitat Politècnica de Catalunya, Barcelona. Vendrell, M., Giráldez, P., González R., Cavallé, F., Roca, P. (2008) Santa Maria del Mar. Study of history and construction, construction materials and structural stability. Report prepared for Generalitat de Catalunya, Barcelona


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8 PARTNER N° 12 – IAA 8.1

7 TYPOLOGIES OF THE BUILDINGS OF THE APP

INTRODUCTION

The built technology in Israel is similar to the historical environment in the Mediterranean Area. We decided that the huge amount of buildings in the Old City of Acco represent special type of buildings are very commune only to the East Mediterranean Countries. We have these buildings all over the coast area and in the historic cities. They represent also the vulnerable structures to earthquakes that are frequent each 100 years in those areas. There are no engineering data about the past earthquakes and only some pictures from the 1927's one. We shall define the chosen buildings for the NIKER project as the - ACCO PILOT PROJECT [APP]. The unusual types in these buildings are the wooden floors anchorage to the exterior walls [WP5] and the slenderness of its exterior walls [WP4]. The buildings of the APP are divided in 7 typologies [WP3]:


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TYPOLOGY I Two to three floors with a cross vault on the ground storey, a wooden flat floor or flat roof on the upper/s story. Many of the buildings have foundations on previous underground vaulted halls or water cisterns. Walls of the ground storey are of sand-lime stone ["kurkar"] with ashlars as exterior leaf and rubble stone on the interior leaf. The mortar is a lime and earth mortar. The upper storey's' walls are lined vertically and about the lower vaulted halls' walls.

Figure 1 – Typology I.

Figure 2 – Typology I.

Typology II Damage based selection of techniques

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Two to three floors with a cross vault on the ground storey, a wooden flat floor or flat roof on the upper/s story. Many of the buildings have foundations on previous underground vaulted halls or water cisterns. Walls of the ground storey are of sand-lime stone ["kurkar"] with ashlars as exterior leaf and rubble stone on the interior leaf. The mortar is a lime and earth mortar. The upper storey's walls are not lined vertically and are built on different sections of the vault of the ground storey.

Figure 3 – Typology II.

Figure 4 – Typology II. Typology III Damage based selection of techniques

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Two to three floors with a cross vault on the ground storey, a wooden flat floor or flat roof on the upper/s story. The foundations are always previous underground vaulted halls or water cisterns of one, two or even three storey under the ground level. Walls of the ground storey are of sand-lime stone ["kurkar"] from the medieval period, ashlars as exterior leaf and rubble stone on the interior leaf. The mortar is a lime and earth mortar. The building is not symmetrical where the ground storey is general perpendicular to the upper storey.

Figure 5 – Typology III.

Figure 6 – Typology III. Typology IV Damage based selection of techniques

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A three floor building with all three flat wooden floors. The foundations are not known. Walls of the ground storey are of sand-lime stone ["kurkar"] with ashlars as exterior leaf and rubble stone on the interior. The mortar is a lime and earth mortar. The building are of rectangular shape, thin walls of equal thickness on all three storey. These are considered slender buildings.

Figure 7 – Typology IV.

Figure 8 – Typology IV. Typology V Damage based selection of techniques

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A three floor building with vaulted ground storey and flat wooden floors on the upper storey. The foundations are not known but most of them are on earthen medieval underground buildings. Walls of the ground storey are of sand-lime stone ["kurkar"] with ashlars as exterior leaf and rubble stone the interior leaf The mortar is a lime and earth mortar. The building are of rectangular shape, thin walls of equal thickness on the upper storey and are called the Captain Houses. These are considered slender buildings.

Figure 9 – Typology V.

Figure 10 – Typology V. Typology VI Damage based selection of techniques

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A three floor building with vaulted halls on the ground storey and first storey and of flat roof on the second storey. The foundations are on earthen underground medieval buildings. Walls of the ground storey and first storey are of sand-lime stone ["kurkar"] with ashlars as exterior leaf and rubble stone on the interior. The mortar is a lime and earth mortar. The building are of square , thick walls of equal thickness on the first two storey and of thin wall on the second storey.

Figure 11 – Typology VI.

Figure 12 – Typology VI. Typology VII Damage based selection of techniques

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An one storey building with a stone arch floor and flat wooden roof connecting two buildings on opposite sides of the street. Foundations are part of the exterior walls of the two buildings. Walls are of sand-lime stone ["kurkar"] with ashlars as exterior leaf and rubble stone on the interior. The mortar is a lime and earth mortar. The buildings are of rectangular shape and thin walls .

Figure 13 – Typology VII.

Figure 14 – Typology VII.


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The failure mechanisms of the related buildings are not different from the usual typologies in the Niker Project. We are here emphasizing the failures mechanisms that are frequent in those Acco's buildings, not related directly to earthquakes that the last one has been in 1927 and not professional recorded.

Figure 15 – Failures I and II.

Figure 16 – Failures type I – Location of anchors.


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Figure 17 – Failures III.

Figure 18 – Failures type III – Failure of vault.

Figure 19 – Failures type III – Concrete floors and galleries.


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Figure 20 – Failures IV.

Figure 21 – Failures V.


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Figure 22

Figures 23-24

Figures 25-26


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