Fatigue assessment of historic retrofitted through-truss riveted railway bridge

Abstract

Fatigue damage has been the most common reason for failure in riveted bridges, with the stringer-to-floor-beams connections being identified as the most prone-fatigue locations by several studies. When assessing fatigue damage of historic riveted railway bridges, the analysis usually considers the structure in its current configuration, disregarding any retrofitting the bridge has experienced during its lifetime. This paper presents a fatigue analysis of a one-century-old riveted through-truss railway bridge, part of the Chilean North-South railway line, considering all interventions made to the superstructure since its construction. To perform the analysis, a detailed train loading spectrum is defined considering historical and current data of freight trains and traffic to generate a realistic loading model for the bridge. FE models are generated for the bridge in all configurations (initial and after each retrofitting), and the fatigue damage is evaluated through S-N curves from the Eurocode. The accumulated fatigue damage obtained by this sequence is then compared with a fatigue analysis of the structure in its current configuration. The comparison shows that the fatigue damage is significantly underestimated when assessing the bridge considering only its current configuration and that the retrofitting can substantially change the structural response at the stringer-to-floor beam connections.