Seismic Response Analysis Of Large-Span Suspension Bridges Under Soil-Pile-Structure Interaction

A numerical model was established to analyze the seismic response of large-span suspension bridges under soil-pile-structure interaction. The soil-pile-structure system was idealized as an integrated planar complex consisting of four-nodded isoparametric elements, beam elements, truss elements and Desai's thin-layer elements along the soil-pile interface. The time domain dynamic analysis by the Newmark-βmethod was divided into the longitudinal planar analysis of the whole bridge system and the transverse planar analysis of the soil-pile-tower system. The geometric nonlinearity of the structure ( the p-△effect and the effect of large deflection) and the material nonlinearity of the soil (represented by the Duncan&Chang nonlinear elastic model) were taken into account.In addition, because the suspension bridge is a large-span structure, the concept of multiple-excitation and pseudostatic displacement was adopted to simulate the travelling wave effect. Further, a computer program in NDP-FORTRAN was developed and the Humen bridge was taken as an example to evaluate the effect of soil-pile-structure interaction, travelling wave and the nonlinear factors upon the seismic response of large-span suspension bridges. Conclusions were drawn from the analysis and this provides practical references for the seismic design of large-span suspension bridges.