Fatigue Performance of Rib-to-deck Joint in Orthotropic Steel Bridge Deck with New Type of Both-Side Fillet Welded Joints

The key fatigue failure modes of rib-to-deck welded joints in orthotropic steel bridge deck (OSD) are fatigue cracks that initiate from toe and root and propagate toward the deck plate. To enhance the fatigue durability of rib-to-deck welded joints, an innovative rib-to-deck joint in OSD with both- side fillet welded joints was proposed. Fatigue performance of the proposed detail was evaluated by the effective notch stress approach, which was compared with the fatigue performance of conventional single-side welding with partial penetration weld detail. The stress range of different penetration rates of both-side fillet welded joints was discussed by finite-element method. The analytical results indicate that both-side fillet welded joints can reduce the maximum effective notch stress amplitude of the weld root and improve the fatigue resistance of rib-to-deck welded joints significantly. Compared with single-side welded joints initiating from weld root, the dominant fatigue failure mode of both-side welded joints is the crack initiating from the weld toe and propagating to deck plate. The results of parametric study indicate the fatigue resistance of novel rib-to-deck welded joints was not distinctly improved by increasing weld penetration ratio.