The influence mechanism of structural characteristics on the fatigue cracking mode at the rib-to-deck welded joint

The fatigue resistance of rib-to-deck welded joints in orthotropic steel decks is primarily governed by the dominant cracking modes, which are influenced by structural configurations and component dimensions. Clarifying the influence mechanisms of these factors on cracking modes can aid in the accurate prediction of fatigue resistance and guide structural design. In this study, the equivalent structural stress method is employed, and an orthogonal test is designed to identify the dominant influencing factors. The influence mechanism of the dominant factor on both crack initiation position and dominant cracking modes is then analyzed. Additionally, structural parameter ranges corresponding to the crack initiation position and cracking mode are established based on the analysis results and real bridge data. The results show that the weld penetration ratio and the weld access hole radius are the primary determinants of crack initiation positions and cracking modes. The weld penetration ratio affects the overall stress distribution of the structure, and increasing it can reduce the probability of crack initiation for each cracking mode. Meanwhile, the weld access hole primarily influences the diaphragm and its adjacent areas. The predicted crack initiation positions and cracking modes within the proposed structural parameter ranges align closely with those observed in real bridges.