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Fatigue of Preloaded Bolted Connections with Injection Bolts

Abstract Injection bolts have been used to replace faulty rivets on strengthening operations of old riveted steel bridges. This technology has been essentially tested for its quasi-static or creep behaviour and there are very few studies concerned the assessment of its fatigue resistance. This paper presents an experimental program developed to evaluate the fatigue behaviour of single shear preloaded bolted connections with injection and standard bolts. Specimens combine S355 steel and old metallic material obtained from structural elements of the centenary Eiffel bridge in Portugal. Fatigue failure was found either at the net cross-section or at a gross cross-section of the plates. Statistical analysis was conducted on the experimental data to compare with the fatigue design curves proposed in Eurocode 3, part 1-9. It is concluded that the detail category suggested on the reference code is not able to represent the fatigue life of old steel materials. An alternative S-N curve is proposed which is able to represent the fatigue behaviour of the studied detail. Furthermore, it was concluded that the influence of the adhesive on the detail’s fatigue strength is not significant.