Fatigue cracks are initiated due to stress concentration and tensile residual stress existing at crack initiation point, and reducing these factors leads to enhanced fatigue strength of the welded joints. The induction heating (IH) is effective to introduce compressive residual stress for welded joints, but there are some problems toward the practical use in fabrication plants or repairing sites of steel bridges. In this study, a newly developed IH application with better workability was applied to the out-of-plane welded joints specimen, and fatigue tests and FE analyses on the specimen were conducted to investigate the improving effect related with the heating conditions and the residual stresses. The results showed that the fatigue strength of the specimen was improved by 2 grades due to the change in the residual stresses.
