Abstract:In order to achieve the better response analysis of river-spanning bridge,the dynamic water and pile-soil-structure interaction are considered. Based on the Poisson equation,Trefftz functions and wavelet theory are used to form the equation to hydrodynamic pressure on pier which is induced by earthquake. Using the linear Morison equation,the formulas to study hydrodynamic energy of the wave forces on piles are proposed. Simultaneity,using the modified Penzien model,the seismic effect on pile-soil-structure was analyzed .Simulation of seismic response for a river-spanning bridge was analyzed with the given theory;and the simulated results show that this approach is simple and effective.