Traction structural stress analysis of fatigue behaviors of rib-to-deck joints in orthotropic bridge deck

Abstract In this study, a traction stress method is adopted for analyzing some of the unique fatigue behaviors observed in a series of recent experimental studies on rib-to-deck joints in orthotropic steel bridge decks. It is found that the traction-based structural stress definition is not only effective for describing the relevant stress state responsible for each of the four fatigue failure modes, but also mesh-insensitive in finite element computation. The latter attribute is essential for achieving a reliable evaluation of the most likely failure mode possible out of four typical failure modes for a given joint design (including exact weld dimensions) under specified loading conditions. As such, effective means of avoiding undesirable failure mode, e.g., Type 4 (i.e., weld root cracking), can be examined, e.g., by increasing either weld fillet size and/or weld penetration. Furthermore, the rib-to-deck joint fatigue test data investigated in this study are shown falling within the scatter band of the traction stress based master S-N curve adopted by ASME Div Code since 2007, implying that data transferability exists among these three sets of test data obtained independently by different laboratories.