Random Response Of Cable-stayed Bridge Under Nonstationary Spatial Seismic Ground Motions

The research shows that the seismic design of the spatial large span results must take into account the spatial variation effect of the ground motion.Based on this,taking the long-span cable-stayed bridge as the engineering background,the influence of the non-stationary spatial variation of ground motion on the seismic response of long-span engineering structures is studied in depth.First,a time-varying coherence function model for spatially varying ground motion is proposed.The model forms a reference to the derivation of the coherent function of the plane wave in a random medium by Fitelson,considering the difference between parallel and perpendicular to the propagation direction of the seismic waves.The time-varying parameters of the model are described by the time-varying parameters.By using the proposed spatially variable ground motion time-varying coherence function model and the power spectrum model of the ground motion,the spectral representation method can be used to simulate the generation of time history curves of non stationary spatial variations.After that,a finite element model of a large span cable-stayed bridge is established by using CsiBridge software.The model structure is half floating structure and the span is 2088 m.At the same time,the dynamic characteristics of the model are analyzed.100 groups of random spatial variations of ground motion samples were simulated by using the artificial synthetic method of non steady vibration proposed before.The ground motion samples are input into the finite element model respectively,and the ground motion responses of the 100 groups of cable-stayed bridges are calculated.By means of the calculation of the main girder,the top displacement and the damper deformation of the cable-stayed bridge,and the statistical mean and standard deviation,the statistical description of the overall seismic response of the bridge is given.Assuming that the stochastic response satisfies the lognormal distribution,the parameter estimation of the response distribution is obtained through the above 100 simulation results,which lays the foundation for the vulnerability analysis of long-span bridges.This paper provides a technical support for further research on the influence of non-stationary spatial variation of ground motion on the structural response of long-span bridges,and also provides reference for aseismic design of long-span cable-stayed bridges.