Wind-Induced Vibrations of the Stay Cables of a Roundabout Flyover: Assessment, Repair, and Countermeasures

This paper presents the results of a multifaceted investigation into the vortex-induced vibrations of the stay cables of a roundabout flyover. Large cable vibrations were spotted during moderate wind speed conditions immediately after the completion of the structure, and after three weeks, because of concerns about the structural integrity of the cable system, temporary restrainers were applied. An investigation was conducted to assess the potential fatigue damage that occurred during that time, combining experimental measurements and a finite-element model of the cable system. As a result, the cable sockets were replaced, causing delays in the opening of the flyover and additional costs. Wind-induced vibration occurred as a result of the very low damping of the cables. Therefore, after the repair, to suppress the phenomenon two differently tuned mass dampers of the Stockbridge type were installed on each cable. The article describes the results of the investigation and presents the methodology used to design efficient damping countermeasures.