Experimental fatigue tests of resin-injected and

Experimental fatigue tests of resin-injected and standard single bolted connections combining S355 mild steel and old material from Eiffel Bridge B. Pedrosa1, J.A.F.O. Correia1,2, C. Rebelo1, A.M.P. De Jesus1, Luís Simões da Silva1

1Department 2Faculty

of Civil Engineering, University of Coimbra, Rua Luis Reis Santos, 3030-788 Coimbra, Portugal of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal

Experimental fatigue tests of resin-injected and standard single bolted connections…

Introduction - Motivation • Prolonging lifetime of old steel bridges • Structural elements with corroded areas and cracks • Innovative methods for repairing and strengthening operations • Implementation of resin injected bolted connections • Fatigue analysis

Bruno A. S. Pedrosa

[1]


Introduction - Objectives • Analyse the influence of using structural adhesives on bolted joints concerning its fatigue behaviour • Study the fatigue performance of injected bolted joints for replacing faulty rivets • Apply injection bolts to connect new plates at the corroded areas of structural elements • Compare fatigue experimental data with fatigue design curves proposed in Eurocode 3, part 1-9

Bruno A. S. Pedrosa

[2]


Experimental campaign Single shear connection configuration were tested to assess fatigue resistance when using injected bolts in comparison to non-injected bolts

A total of 24 specimens were tested (number of trials – 3): • 4 tests varying the stress range: High, Medium and Low • 2 tests varying the type of bolt: Injected and Non-Injected Specimens are composed of new steel (S355) and old steel obtained from structural elements of Eiffel bridge

Bruno A. S. Pedrosa

[3]


Bruno A. S. Pedrosa

[4]

Materials - Steel Plates The experimental program includes plates composed of S355 steel and plates machined from original structural elements replaced on Eiffel bridge, Viana do Castelo. Both types of steel plates were manufactured respecting the geometry presented below. Eiffel bridge

Plate’s geometry

The Eiffel bridge was inaugurated in 1886 and was built in puddled iron, which is a material with many heterogeneities, responsible for significant scatter in material properties.


Bruno A. S. Pedrosa

Materials - Bolts

Each test specimen includes: • Two M24 bolts

Injection bolts were adapted following the recommendation in Annex K of EN 1090-2.

Bolts were tightened using the torque method considering the procedure described in EN 1090-2.

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• Class 10.9

As

fub

Fp,C

Mr

[MPa]

[kN]

km -

d

[mm2]

[mm]

[kN.m]

353

1000

247

0,123

24

729


Bruno A. S. Pedrosa

Materials - Resin/Adhesive An epoxy resin was used with a commercial name Sikadur®-52. It is a two-part epoxy resin. Properties: • Low viscosity • Good adhesion to steel • Acceptable mechanical properties

Component A

Component B

Mixture A + B (2:1)

Mechanical properties of Sikadur®-52 Compressive Strength Shear Strength Cure time (+23ºC) (+23ºC) 7 days Aprox. 52 MPa Aprox. 61 MPa

Tensile Strength (+23ºC) Aprox. 37 MPa

[6]


Bruno A. S. Pedrosa

Experimental Procedure Fatigue tests were carried out under load control:

- Force Range, ΔF - Maximum Force, Fmax

Stress Ratio: Frequency:

R=0.1 F =5 Hz

Walterbai Multipurpose Servohydraulic Universal Testing Machine Series LFV 600 kN

[7]


Bruno A. S. Pedrosa

[9]

Experimental results Specimen

Medium Cycle Fatigue

Nf

[Hz]

[MPa]

[MPa]

cycles

108

5

158,5

214,0

325.628

0,1

120

108

5

156,3

211,1

175.045

0,1

120

108

5

152,6

205,8

57.990

x

0,1

120

108

5

160,0

215,9

349.915

0,1

120

108

5

156,6

211,6

29.028

x

0,1

120

108

5

156,7

211,5

277.647

x

Rσ

7 (A7 + F7)

0,1

100

90

5

128,8

173,9

50.725

8 (A8+ F8)

0,1

100

90

5

130,7

176,1

675.759

0,1

100

90

5

133,2

180,0

92.855

0,1

100

90

5

135,6

182,8

574.138

0,1

100

90

5

132,7

179,4

531.952

0,1

100

90

5

129,4

174,8

413.977

9 (A9+ F9) 10 (A10 + F10) 11 (A11 + F11) 12 (A12 + F12)

High Cycle Fatigue

Δσ net

120

5 (A5 + F5) 6 (A6 + F6)

Δσgross

[N]

3 (A3 + F3) 4 (A4 + F4)

f

0,1

1 (A1 + F1) 2 (A2 + F2)

Fmax

ΔF [N]

Resin Injected

x x x

13 (A13 + F13)

0,1

85

76,5

5

111,0

149,5

5.087.414

14 (A14 + 14)

0,1

91,75

82,575

5

121,0

163,0

601.553

15 (A15 + F15)

0,1

89

80,1

5

117,5

158,8

905.699

0,1

89

80,1

5

115,0

155,0

703.018

0,1

89

80,1

5

115,8

156,0

1.289.745

0,1

89

80,1

5

118,6

160,0

1.667.047

16 (A16 + F16) 17 (A17 + F17) 18 (A18 + F18)

x x x


Experimental results •

Specimens with Resin Injected Bolts increase the fatigue strength for high-cycle fatigue

•

Mean S-N curve for Standard Bolts is similar to EC3 detail 90

•

Runouts were excluded from the statistical analysis

Bruno A. S. Pedrosa

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Fatigue Failure Analysis

Bruno A. S. Pedrosa

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Conclusions •

Sikadur®-52 showed good qualities concerning the injection process (low viscosity, rapid cure time)

•

Scatter obtained on experimental results may be a result of inclusions and heterogeneities presented on Eiffel steel plates.

•

Resin improved the fatigue strength of bolted connections in high-cycle regime.

•

The fatigue design curve proposed in EC3 is unsafe for nearly half of the results, however, it has a slope similar to the mean S-N curve obtained for standard bolts.

Bruno A. S. Pedrosa

[12]

Análise à Fadiga de Ligações Aparafusadas Com Adesivos

Bruno A. S. Pedrosa

Thank You!

[13]

Experimental fatigue tests of resin-injected and standard single bolted connections combining S355 mild steel and old material from Eiffel Bridge B. Pedrosa1, J.A.F.O. Correia1,2, C. Rebelo1, A.M.P. De Jesus2, Luís Simões da Silva1

1Department 2Faculty

of Civil Engineering, University of Coimbra, Rua Luis Reis Santos, 3030-788 Coimbra, Portugal of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal