Keeping cables calm

Cable vibration and corrosion are potential problems relating to cable-stayed bridges. Nonetheless, owners think their structural elegance is worth it, and increasingly longer cable-stayed bridges are being built worldwide. In Japan several cases of unexpected vibration occurred in cable-stayed bridges and the findings of several research committees are reported. In one case, the bridge was a pedestrian bridge, and the way crowds walked on the slightly swaying bridge contributed to the vibrations. Several corrective methods, including tuned mass dampers were used to correct the problem. On another bridge, wind and rain effects contributed to the unanticipated cable vibration. After much study, designers developed several methods to prevent these effects. One is to place cables in a tube with short fins that prevent cross section distortion when it rains. This method was used for the first time on the new Higashi-Kobe Bridge. Another is to insert dampers between the cable and the deck. Viscoelastic dampers are becoming popular for cable-stayed bridges.