Abstract：Wuhan Junshan Yangtze River Bridge has experienced significant fatigue cracking on the deck plates after a service period of six years, and they are difficult to repair. Thus, a novel UHPC-based strengthening technique with steel strips for repairing the OSDs with significant fatigue cracks is proposed. Two types of bridge deck systems, OSD and conventional lightweight steel-UHPC deck (LWCD), were analyzed with the submodel technology to get the stress. The conventional LWCD specimens with two-story bars and two types of modified LWCD specimens with steel strips and three-story bars were manufactures, and the static and fatigue tests were performed. The analysis results indicate that the conventional LWCD can significantly reduce the fatigue details stress, and the transverse tensile stress distribution around the rib-to-deck welded joints can be reduced by 78.8%-86.4%. Under the vehicle load, the maximum design tensile stress at the bottom of UHPC layer was 12.9MPa. The tensile strength of UHPC layer strengthened by 80mm-width steel strips could reach 43.2MPa, which is much higher than the designed stress. Basing on the 10 million fatigue-loading cycles test results of the steel strips strengthening scheme, it is concluded that the UHPC layer has 8 million cycles fatigue life (the crack width is less than 0.05 mm), therefore the permanent UHPC structure layer and the severely cracked steel bridge deck can constitute a lightweight composite bridge deck structure. By the proposed strengthening technique, the fatigue cracking of the deck plate will be well controlled.
