Visual inspection of the Innoshima Bridge's suspender ropes, conducted in 1997, revealed rust on the external surfaces of the suspender ropes, and rusty water oozing from the rope surfaces near the sockets. In 1999, two suspender ropes were removed from the bridge, and disassembled and inspected for internal corrosion. Local corrosion was identified inside the ropes though not serious enough to have an adverse influence on the rope strength. The inspection results showed that the locations of internal corrosion did not correlate with the external appearance of the ropes, and that internal corrosion cannot be detected by external visual inspection alone. Under these circumstances, the authors developed a nondestructive inspection technique that uses an electromagnetic method (main flux method) to identify internal corrosion of suspender ropes from the exterior. (Author/publisher) For the covering entry of this conference, please see ITRD abstract no. E208431.
Abstract