Stochastic Seismic Response Analysis Of Hybrid Girder Cable-Stayed Bridge

The cable-stayed bridges have developed rapidly in recent years, the span of the cable-stayed also increased from hundred meters to km level, with the increasement of the span, the seismic design for cable-stayed bridge is becoming more and more complicated, so it is quite necessary to make seismic analysis for cable-stayed bridge. It is reasonable to use the stochastic method to analyze seismic response of cable-stayed bridge as earthquake is a random process.Using the finite element analysis software ANSYS and taking edong bridge as the engineering background, the seismic response of hybrid girder cable-stayed bridge is calculated under uniform and non-uniform excitation with the stochastic method, the mechanism of the seismic response is discussed through analyzing the response power spectrum. Based on calculation, the following conclusions are drawn:the longitudinal seismic response of the bridge is much larger than transverse and vertical response under longitudinal uniform excitation; The characteristics of seismic response under transverse uniform excitation is similar to the response under longitudinal excitation:transverse seismic response is much larger than that under longitudinal excitation and vertical excitation; However under vertical uniform excitation, the vertical response of the bridge is largest, but the longitudinal and transverse response cannot be ignored; The seismic response of the structure under 3d uniform excitation is much larger than the response under one dimensional uniform excitation.Seismic response analysis of the bridge under non-uniform excitation with spatial variations, including traveling wave effect, incoherence effect and local site effect, was made with stochastic method. The results show that the responses obtained by considering traveling wave effect are smaller than those under uniform excitation, the responses obtained by considering incoherent effect are significantly larger than those without considering the coherent effect and slightly smaller than those considering completely coherent; The responses of the structure after considering local site effect are almost the same with those under uniform excitation, thus the influence of local site effect on seismic response of structure is not obvious.For hybrid girder cable-stayed bridge, the internal force of side span is much larger than that of main span and the displacement of side span is much smaller than that of main span. Based on the response power spectrum, the modes of vibration those contribute to the seismic response under various excitation conditions are determined, and then the mechanism of the seismic response is expounded.