Fatigue failure modes of rib‐to‐deck joints under the multiaxial stress states caused by various wheel loading characteristics

Orthotropic steel bridge decks (OSBDs) are characterized by overall structural asymmetries and severe local stress concentrations; meanwhile, complicated service loadings always cause relevant rib‐to‐3deck (RD) welded joints in multiaxial stress states. Under such circumstances, a full‐scale OSBD model was established. Six loading cases were applied, and the multiaxial fatigue deviation was calculated to represent the multiaxial stress state of the bridge deck. Based on the effective traction structural stress method, the most unfavorable loading case for the failure mode of the RD joint under a multiaxial stress state was analyzed, and the failure mode transition in the process of wheel load movement was discussed. The results indicated that the fatigue failure mode of the RD joint was determined by the transverse loading locations. In‐between‐rib loading can cause the initiation of toe‐rib cracks. Cracks are prone to occur under over‐rib loading and riding‐rib loading, and the arrangement of diaphragms can increase the risk that the fatigue crack originates from the weld root. Highlights Multiaxial stress for rib‐to‐deck joints in various wheel loading cases was calculated. Equivalent structural stress was calculated to analyze the fatigue failure modes. Effect of wheel loading position and quantity on the fatigue failure mode were discussed. Failure mode transition for welded joint in the wheel load moving process was analyzed.