Full-scale investigations of cable vibrations on cable stayed bridges and development of a cable damper using viscoelastic material.

摘要

The first part of the thesis summarises the theory of cable vibrations. Cables of cable stayed bridges behave mostly like taut wires, the influence of gravitational stiffness is not significant. The amplitude of cable vibrations generally has a magnitude of several centimetres, but can exceed 1m in the first mode. A sufficient level of damping to suppress strong vibrations is 0.6%-0.7% of critical.;Cable vibrations of Weirton-Steubenville Bridge, West Virginia, were measured. A significant share of these vibrations was caused by traffic. Wind vibrations occurred preferably with wind from directions close to the bridge axis. The drag crisis effect seems to cause most wind induced vibrations. Rain is involved in some of the strongest vibrations, but more data should be collected to confirm a dependency. The maximum observed amplitudes were in the range of 30 cm and caused striking of adjacent cables.;A damping system for cables is suggested, based on viscoelastic material. Compared to dashpot damper or cable cross ties, the viscoelastic damper has the advantage of being easily built in and not influencing the aesthetics of the bridge. A disadvantage is the dependency of added damping on temperature. A model damper was built and tested. The experiment showed that the formulas describe the physics of the damper and can predict the damping.;A damper is designed for the cables of Weirton-Steubenville Bridge. The damper is effective and functions. At 20