Fatigue Strengthening of U-Rib Butt Welds in Orthotropic Steel Bridge Decks Using CFRP Sheets

U-rib butt weld is one of the most important components in early orthotropic steel bridge decks, which plays a critical role in connecting the segments of steel box girders. However, fatigue cracks are prone to produce, and it will threaten the driving safety and reduce the reliability of the bridge structures. CFRP has been broadly adopted in the field of civil engineering reinforcement by virtue of its excellent performance. Pasting CFRP sheets to the U-rib butt weld can achieve non-destructive repair of the structures, thereby improving the fatigue performance of the fatigue detail. In this paper, two single U-rib specimens were designed and the real fatigue cracks were produced under the fatigue loading. Then strengthening method of pasting CFRP sheets were presented and fatigue strengthening test of cracked U-rib butt weld specimens were performed. The results showed that the average fatigue strength of the cracked welds after reinforcement at 2 million cycles is 76 MPa, and the average fatigue life can be increased by 2.3 times.