Fatigue test and failure mechanism of new rib-to-floorbeam welded joints in OSDs

To improve the fatigue performance of rib-to-floorbeam (RTF) welded joints in orthotropic steel decks (OSDs), a new RTF welded joint was proposed in this study. The full-scale segment fatigue tests including the traditional and new RTF welded joints were carried out, and the fatigue performance of new RTF welded joints was eval-uated. The fatigue failure mechanism was analyzed by using numerical simulation. The results show that the fatigue crack initiation appears at the weld toe of the bottom rib of the new RTF welded joint, while the fatigue crack of the traditional RTF welded joint initiates at the end of the weld toe. Besides, the fatigue crack propa-gation rate of the new RTF welded joint is remarkably lower than that of the traditional RTF welded joint. The new RTF welded joint is about twice fatigue life of the traditional RTF welded joint. The weld residual tensile stress (WRS) is the main factor in the fatigue crack initiation of RTF welded joints subjected to compression-compression cyclic loading.