Displacement Monitoring of Expansion Joints of Long-span Steel Bridges with Viscous Dampers

This paper presents the displacement monitoring of expansion joints of long-span steel bridges, with emphasis laid on the effect of viscous dampers. Monitored data from the Sutong Bridge and the Jiangyin Bridge were analyzed and compared with those of the Runyang Suspension Bridge. Decomposition of displacement signals in various frequency bands shows that the temperature-induced movements are only a very small portion of the total cumulative displacements, while - due to the small but fast movements caused by vehicle/wind loads - the cumulative displacements of long-span steel bridges may be very considerable. The viscous dampers can reduce the vehicle/wind-induced displacements but have no significant influence on the temperature-induced movements. In addition, the measured temperature-displacement relationships of the Sutong Bridge are not linear ones (as reported previously), but are hysteretic due to the time delay between temperature and displacement signals.