Research On The Response Of The Long Span Cable-Stayed Bridges To The Multi-Support Seismic Excitation

Earthquake is a highly destructive natural disaster which occurs frequently and unpredictably. As the key transportation project, Once the cable-stayed bridge subjected to destruction, there would be seriously direct and indirect losses of life and property, and with the rise of long span cable-stayed bridge construction projects in recent years, it becomes more and more urgent and necessary to do the research on the seismic analysis of long span cable-stayed bridge.For the long span cable-stayed bridge with the span of hundred meters or even kilometers, the seismic response analysis method based on the assumption of uniform excitation can not meet the requirement because it is necessary to analysis the multi-point seismic response under the consideration of earthquake time and space variability.A series of works about the seismic response analysis of long span cable-stayed bridge has been done in this paper as follows:Firstly, the spatial correlation of non-stationary artificial seismic wave theory and numerical simulation methods was introduced. It was introduced in details about the basic theory and method on how to make artificial seismic waves with the method of trigonometric series. And the coherence function and phase spectral function which are used to consider the spatial correlation of ground motion and non-stationary nature was introduced. Based on the theory, the artificial seismic program which can consider the spatial correlation of ground motion and non-stationary nature was made in this paper.Secondly, the nonlinear problems of long span cable-stayed bridge and the finite element method are expounded. Then, it is introduced about the way to modeling the cable-stayed bridge on the dynamic analysis. Based on the theory of nonlinear finite element, nonlinear equations of motion about the multi-DOF structural system under the uniform seismic excitations, wave passage effect and multi-suppot excitation are established, and the method to solve these equations is inferenced in details. Based on these theorise, the finite element program which can solve the static and dynamic nonlinear plane finite bar elements problem under the earthquake is written by using MATLAB.Finally, background with a long span cable-stayed bridge and by using the own written program as the analysis tool, seismic response analysis of the cable-stayed bridge under uniform seismic excitations, wave passage effect and multi-suppot excitation is studied with time history method in this paper. Some conclusions that are useful for the the seismic analysis of long span cable-stayed bridge engineering are found, which can be provided as some reference and basis.