Detection and monitoring by FSM for fatigue crack at invisible location of steel plate deck with U-rib

For verifying the applicability of FSM, which is one of the non-destructive inspections based on the potential difference method, for fatigue cracks generated at the invisible location of a steel plate deck with U-rib, a series of experiment and numerical analysis was carried out. In the fatigue experiment, it was confirmed that cracks initiated at the roots of the welds between the deck plate and the U-rib. They propagated concentrically from the roots into the thickness direction of the deck plate. The FC values obtained by the static electric field analysis were agreed with the experimental results. It was indicated that the initiation and propagation of fatigue crack could be detected and monitored by FSM. It was known that the crack initiation at either welds of the left or right sides of the U-rib could be judged by noting the behavior of the FC value of the pair. It was confirmed that the initiation and propagation of fatigue cracks could be detected and monitored with high accuracy by FSM with noting the FC value of the pair possible to be used actually.