Research on Fatigue Strengthening of Deck-to-U Rib Welds of Orthotropic Steel Deck via Sticking Reinforcement Plates on Deck Surface

In this paper, a fatigue strengthening method of sticking reinforcement plates on the surface of steel deck to address the cracking issue of deck-to-U rib welds of orthotropic steel deck is proposed.The method is illustrated by a case study of a suspension bridge with a main span of 1 490 m.A local finite element model of the orthotropic steel deck was developed, based on which the stress condition of the deck-to-U rib welds was calculated when the wheel loads were applied along bridge width and when vehicles were moving on the deck.The effects of parameters, including the thickness, dimensions(in both the transverse and longitudinal directions) and material properties of the reinforcement plate, were analyzed.Combined with the linear cumulative damage theory and the measured traffic volume, the fatigue life of welds of different strengthening solutions were compared.According to the study, the stresses in the deck-to-U rib welds can be lowered, either using the steel or CFRP reinforcement plates.The thickness of the reinforcement plate is substantial to the strengthening effect, the dimension of reinforcement plate in the transverse direction shows limited influence on the strengthening effect, and the influence of reinforcement plate dimension in the longitudinal direction is negligible.The strengthening effect of steel reinforcement plate outweighs the CFRP reinforcement plate.When the steel and CFRP reinforcement plates of dimension of 400 m(length in the transverse direction)×8mm(thickness) are applied, the fatigue lives of the deck-to-U rib weld after strengthening are improved by 90.85% and 66.15%, respectively. © 2022, Journal Press, China Railway Bridge Science Research Institute, Ltd. All right reserved.