Research On The Seismic Performance Of Long-Span Cable-Stayed Bridge

Long-span cable-stayed bridge is a transportation hub project, which has a significant impact on the national economy, and once which is damaged in the earthquake, will result huge losses directly or indirectly. Therefore, the research on seismic behavior of long-span cable-stayed bridges is necessary.The seismic behavior of Fengdu Yangtze River second bridge, a long span semi-floatinghybrid cable-stayed bridge with two towers and double cable planes, is investigatedbased on the anti-seismic research work that has been done domestic and abroad.Based on the theory of finiteelement method, three dimensional finite element model is established and the vibration characteristics and seismic response of the bridgeare researched with the model. The main work in this thesis as follows:(1) The development of seismic analysis methods for bridge is expounded andthe basic principle of response spectrum and time-history analysis method for bridgeis introduced.(2) Spatial finite element dynamic calculation model of the whole bridge is developed, using appropriate element type, according to the structural feature of thebridge by advanced analysis program ANSYS.By analyzing the vibration characteristicsof the FEM model mentioned above, the vibration characteristics of long-spancable-stayed bridge are summarized.(3) By calculating the cumulative effective mode participation mass of thebridge, the minimum number of modes for response spectrum analysis is obtained.Design acceleration response spectrum is selected according to the site condition ofthe bridge to calculate the seismic response of the bridge under two load conditions, namely, longitudinal, transverse, vertical and the combination of horizontal andvertical and the seismic response of the bridge under P1, P2 probabilities is alsochecked.(4) According to the site condition of the bridge, appropriate ground motionrecord is selected for the time-history analysis. Two seismic waves and an artificial wave are chosed, PI and P2 are calculated under two levels of probability, Fengdu Yangtze River second bridge Seismic response time history analysis, and explores the two conditions of seismic excitation on seismic response effect.