Abstract
Recently, many fatigue cracks are observed at welded toe of steel bridges. Fatigue cracks initiated at actual bridge is generaly inspected by magnetic-particle test, MT. However, in case of inspection by using MT, removal of painting and re-painting takes a lot of time and cost, and MT can not inspect wide area at one time. Therefore, in this study, by visualising propagation of surface acoustic wave by using image processing, it is clarified whether fatigue cracks initiated on the painted steel member can be detected or not. As the results of measurement results, fatigue cracks initiated at painted out-of-plane gusset joint or T gusset joint can be detected even if painting cracks are generated. However, fatigue cracks initiated at the painted welded joint can not be detected in case that both of peeling and cracking of painting are generated.
