ABSTRACT
U-rib butt welded connection is one of typical fatigue prone details in orthotropic steel bridge decks (OSDs). The U-rib butt welded connection plays a role in connecting longitudinal beams in the bridge deck system. Once the U-rib butt weld cracks, it will reduce the stiffness of the bridge deck system and threaten the safety of the bridge structures. In this case, the immediate need is to find an effective reinforcement method. This paper proposes a novel Fe-based shape memory alloy (Fe-SMA) bonding reinforcement method for cracked U-rib butt welded connection in OSDs. The innovative Fe-SMA materials can proactively produce prestressing recovery stress by thermal activation and introduce residual compressive stress closed to crack tips, resulting in extending fatigue life of structures. Two full-scale single U-rib specimens were in-itially subjected to fatigue load to generate fatigue cracks. Then the cracked U-rib butt welded connections were strengthened by externally bonded Fe-SMA plates, and fatigue test was conducted to investigate the effectiveness of Fe-SMA bonding method. The experimental results showed that the active reinforcement method can significantly improve the fatigue performance of U-rib butt welds. The Fe-SMA plates can generate 20–59.1 compressive stresses in the U-rib butt weld areas. The average fatigue strength of the reinforced specimen is 130MPa.
