Effects of expansion devices and dampers on additional forces in a suspension bridge

Abstract

Suspension bridges are flexible cable structure systems with substantial geometric nonlinearity, and their mechanical characteristics are quite different from those of other types of bridges. The bridge-track interaction of long-span suspension railway bridges is considerably more complicated than that of other types of bridges. In previous studies, the expansion devices and dampers were always ignored to simplify the track-bridge system when calculating the additional forces in long-span bridges, reducing the accuracy of the calculation results. In the present study, the effects of expansion devices and dampers on the additional forces of continuously welded rails (CWRs) are investigated on the basis of the Wufengshan Yangtze River Bridge, the longest high-speed railway suspension bridge in the world, with a main span of 1092 m. The bridge-track spatial model of the bridge, including the rail expansion joints (REJs), is built using the principle of the double-layer spring model. The resistance of the ballast and fasteners is simulated by bilinear models. The effects of the expansion resistance of the REJ and damper equivalent stiffness on the additional forces on the rails are investigated through bridge-track interaction analyses. The results show that the expansion resistance of the REJ has little effect on the additional force on the rails but substantially affects the horizontal force and displacement of the fixed piers. Under braking conditions, the damper equivalent stiffness substantially affects the additional force on the rails. The bridge tower bears a larger horizontal force as the damper equivalent stiffness increases.