Fatigue behavior in the Floorbeam region of new open-rib orthotropic steel deck

To mitigate the risk of fatigue cracking in orthotropic steel decks (OSDs), this study proposed a new open-rib orthotropic steel deck (NOSD). The NOSD incorporates spherical flat steel open ribs and apple-shaped cut-outs in the floorbeam. The fatigue performance in the floorbeam region of the NOSD was evaluated through numerical analysis and fatigue tests and compared with that of a conventional double-sided welded U-rib orthotropic steel deck (UOSD). The results indicate that the NOSD effectively eliminates the fatigue cracking mode at the rib-to-deck welded joint, ensuring that this area is no longer fatigue critical. Under the most unfavorable loading conditions, the primary factor contributing to fatigue damage on the floorbeam side of the rib-to-floorbeam welded joint of the NOSD is out-of-plane stress, whereas in-plane stress is the main fatigue damage factor in the arc cutouts. Compared with the UOSD, the NOSD exhibited a significantly longer fatigue life, highlighting its enhanced fatigue resistance. The fatigue cracking modes in the floorbeam region of the NOSD include cracks initiating near the weld toe on the floorbeam side and propagating upward along the weld, as well as cracks starting at the arcs of the two cutouts, expanding toward the center, and ultimately intersecting.