In North America and Europe, there is a significant number of centenary metallic bridges that require maintenance and strengthening operations. These structures need to be adapted to increasing traffic intensities, and their structural integrity should be constantly evaluated. Fatigue damages were not considered in the original design of old metallic bridges, and riveted connections are one of the most frequent sources of fatigue damages on these structures. This paper intends to be a contribution for the reliable assessment of the fatigue behavior of riveted connections by proposing S-N curves for these structural details. Experimental fatigue data is analyzed from multiple bridges across Europe, and different statistical methods were implemented. A normal distribution function was implemented following the ISO 12107 standard, and the results were compared with the implementation of the two-parameter Weibull distribution function. Different estimation methodologies were implemented to determine the parameters of the Weibull distribution. S-N curves obtained by the statistical analysis were then compared with design recommendations from North American and European standards.

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.