Rewelding Repair Effects on Fatigue Cracks in Steel Bridge Deck Welds

Specimens of rib-to-deck welds and diaphragm-to-rib welds in steel bridge decks were tested to crack under cyclic load. The cracks were repaired by rewelding. After the rewelding, other treatments were considered, including polishing, heat treatment, and strengthening with carbon fiber-reinforced polymer (CFRP). Fatigue tests were again conducted on the repaired specimens. The microstructure of the rewelded areas was observed using a metallurgical microscope. The position and propagation of the new cracks were discussed to evaluate the efficacy of the repairs. The results indicated that new cracks occurred in the rewelded zone. After the initial cracking of roof-to-rib welds, crack propagation remained at a similar speed. Polishing, heat treatment, and CFRP strengthening can improve the fatigue life after a rewelding repair; the best rewelding timing is suggested to be the intermediate stage of crack propagation. The fatigue life after rewelding is determined by the new weld. (C) 2017 American Society of Civil Engineers.