ABSTRACT
ABSTRACT: This paper presents a rational procedure for evaluation of fatigue crack formation that has been repeatedly detected in cantilever brackets which support the region of the guard rails of a steel box railway bridge. The case study herein considered is a horizontally curved steel box girder bridge composed of 9 spans, with length of 35 m. This bridge is located in the VitóriaMinas Railway, one of the main Brazilian “heavy axle load” (HAL) railroads, mainly used for the transportation of iron ore and general cargo. Recently, the structure received interventions after detection of cracks in the vicinity of welds between the cantilever brackets and the primary box girder. An investigation based on field measurements and finite-element analysis has been performed to identify the causes of these cracks. The purpose of the numerical analysis has been also to provide insight on the structural behavior before and after the bridge rehabilitation. The study suggests that cracking is induced by secondary displacements, which occurs mainly in the regions close to the abutments, where the global rotations are unrestrained. The results and the main conclusions validating the applied methodology are presented in this paper.
