Abstract:

In this paper, by taking the Sidu River Bridge as the example, a spatial dynamic model of long-span suspension bridges with steel truss stiffening girder is established, and the nonlinear motion equations in the multisupport excitation condition are deduced based on Leger＇s large-mass method （LMM） and the pseudo static displacement conception. Then, a 3D nonlinear time-history analysis of the seismic response of the bridge is performed, and the effects of soil-pile-bridge interaction and central buckle configuration on the seismic response are investigated. The results show that the effect of soil-pile-bridge interaction on the seismic response of suspension bridge is closely related to the excitation ways of seismic ground motion and is greatly affected by the horizontal component of seismic wave but slightly affected by the vertical component, that a pair of flexible central buckles has adverse effect on the longitudinal displacement and the stress response of stiffening girder, while a pair of rigid central buckles and three pairs of flexible central buckles significantly restrict the longitudinal displacement of stiffening girder although the seismic stress response of the structure greatly increases in this case.

Key words: long-span suspension bridge, seismic response, influence factor, time-history analysis, central buckle, soil-pile-bridge interaction