Fatigue performance of welded joint between thickened-edge U-rib and deck in orthotropic steel deck

This study investigates the fatigue performance of an innovative rib-to-deck welded joint linking the longitudinal U-rib and deck plate of orthotropic steel deck (OSD). The welded joint has an increased weld depth due to the rolled U-rib with thickened edges. Seven large-scale OSD specimens, including three conventional OSDs and four OSDs with the rolled U-ribs, were tested under static and cyclic loadings. The static loading tests indicate that the welded joint may significantly change the stress distribution around the rib-to-deck joint. Fatigue tests were carried out to investigate the damage propagation process, failure mode, and fatigue resistance. The effective notch stress method is employed to evaluate the fatigue properties and failure mechanism. For both types of the OSD specimens, the predominant failure mode was cracking at the deck weld root. The fatigue resistance of the specimens that had different U-ribs were comparable, indicating that the use of the rolled U-ribs did not significantly increase the resistance to the fatigue cracking initiated at the deck weld root. This study suggests that the evaluation of fatigue resistance must be performed based on the specific failure mode.