Damping of long-span suspension bridges with damped outriggers

Long-span suspension bridges are vulnerable to vortex-induced vibrations (VIVs), e.g., the Humen Bridge and the Xihoumen Bridge in China. This study focuses on a novel strategy by using damped outriggers to control rotations of bridge deck at the junction points between the girder and a bridge tower or pier. A simplified model of a suspension bridge with damped outriggers is used for damping analysis. Considering practical parameter ranges, the maximal damping ratio provided by one damped outrigger to a specific mode is about 1.0%. Influences of bridge boundary conditions, installation position of damped outriggers, and interaction between multiple damped outriggers are studied. When multiple damped outriggers are installed, the damping effects of multiple modes can be further improved. It is shown that damped outriggers are effective in suppressing multimode vibrations of long-span suspension bridges.