Fatigue Test of CFRP-strengthened U-rib Butt Weld in Steel Bridge Decks

Abstract:

In order to explore the fatigue cracking mechanism and strengthening methods of U-rib butt welds in steel bridge decks， a total of two full-scale single U-rib specimen models with embedded sections were designed， and the fatigue failure modes and actual fatigue resistance of the detail were investigated through model tests. Then， based on the linear elastic fracture mechanics method， a butt-weld cracked model repaired by CFRP strips was established， and the effects of the number of layers and the size of CFRP cloth on the fatigue performance were investigated through numerical simulation. Finally， the non-destructive repair methods and construction process of pasting CFRP strips were introduced for the U-rib butt welds， and the fatigue test of the cracked specimens repaired by CFRP strips was carried out. The results indicate that the fatigue vulnerable points of the U-rib butt welds all appear at the arc transition of U-rib， and the average fatigue strength is only 59.7 MPa. After being repaired by three layers of CFRP strips， the fatigue strength of the welds with different damage degrees is about 0.8 to 2.6 times of unrepaired specimens. Pasting CFRP strips can effectively improve the fatigue performance of the U-rib butt weld details of the steel bridge decks， and meet the demand for the non-destructive repair of actual bridges.

Key words:bridge engineering;butt weld;carbon fiber strips;crack repair;fatigue strengthening