Vibration reduction for expansion joints of long-span suspension bridges using frictional dampers

Excessive vehicle-induced cumulative longitudinal displacement of girder ends in long-span steel bridges is a major cause of early damage to the expansion joints. Although viscous dampers are usually used as longitudinal vibration reduction devices, oil leakage and sensitivity to temperature variation are often observed in practice. This study proposes a longitudinal vibration mitigation strategy for expansion joints of long-span bridges using frictional dampers, which has been rarely studied on bridges. First, the restraining effect of the damper on a single vehicle load is investigated, and a considerable reduction in girder end displacement is observed. The damping force and displacement curves demonstrate that the slip-elastic mechanism of frictional dampers effectively dissipates energy during motion. Furthermore, the dynamic behaviors of long-span suspension bridges under traffic loads are analyzed through the stochastic flow generation technique. The girder end displacement gradually decreases with an increase in the elastic stiffness and sliding yield force. Finally, a rational frictional damper design method is proposed and discussed. This study explores a pioneer application of frictional dampers on large-span steel bridges.