This paper presents a study on cyclic flexural behavior of thickness-reduced steel pipe repaired by welded patch plates. In this study, cyclic flexural tests of repaired pipes are performed, and the experimental results are compared with finite element (FE) analyses. In FE analyses, several combinations of patch plate thickness and reduced pipe thickness are modeled. From numerical results, the buckling behavior of thickness-reduced steel pipe repaired by patch plate is explained. It is shown that a required thickness of patch plate is larger than the thickness reduction to achieve the same level of ductility performance in the repaired pipe.
