Ultra Kilometer Span Highway And Railway Cable Stayed Bridge Seismic Response Analysis Under Spatial Effects Of Ground Motion

With the development and improvement of China’s public and railway network, a large number of cross river bridge has been put on the agenda, this kind of long span bridge is important node of the main traffic route, once damaged, it will cause enormous economic loss. Therefore, it is of great significance to study the seismic response of super long span bridges which are important nodes in traffic lifeline. In view of this, many scholars have conducted in-depth research on the seismic response of the bridge structure.This dissertation is based on time history analysis method and high efficiency virtual excitation method,for double purpose cable stayed bridge with over kilometer span, the influence of spatial effect on seismic response of the bridge structure is studied in detail,the acceleration time history curve and the ground acceleration power spectrum of the virtual excitation method are calculated by the same acceleration power spectrum model,and the response of the above two methods are analyzed and compared in order to emphasize the necessity of considering spatial effect.The content framework is as follows:1.The acceleration power spectral density function model and partial coherence function model of random vibration field studied by domestic and foreign scholars are listed.And the dissertation selected the power spectrum density function model and partial coherence function model which are suitable for the double purpose cable stayed bridge with over a kilometer span,and the relevant parameters of the model are picked up from the specification.2.Large commercial finite element software Ansys is used to establish three-dimensional finite element model, and analyze the dynamic characteristics of bridge condition,Studied the construction state of bare tower for the random seismic response analysis and in three-dimensional seismic considering local site effect, wave passage effect, the coherent effect on seismic response of bridge structure influence.3.Use MATLAB software to show seismic wave synthesis theory,and under the same power spectrum, apply the virtual excitation method model to synthesize artificial seismic wave, and analyze the time history of the construction state of bare tower.4.The dissertation compared the response of the construction state of bare tower obtained by the harmonic analysis and time history analysis.