Seismic Response Anlysis Of Long-Span Multi-Tower Cable-Stayed Bridges

Modern Cable-stayed bridges are being developed toward longer span accompanied by severe temperature effect. To minimize the temperature effect of modern cable-stayed bridges effectively, many new types of bridge expansion devices are brought to use. However, more research should be conduct toward these new bridge expansion devices.Based on the basic theory of the seismic response analysis as well as the plan of Qiongzhou Strait Bridge, the main target of the thesis is to analyze the seismic response of the long-span four-tower cable-stayed bridge as well as its bridge expansion device by time history method. This paper contains the following parts:1.To summarize the history of cable-stayed bridge and its trend of development, elaborate the major method of modern seismic analysis;2.Establish a spatial finite element model of a four-tower cable-stayed bridge based on the plan of Qiongzhou Strait Bridge. Based on the traveling wave effect, use the multi-support excitation time history method to analyze the dynamic response of the four-tower cable-stayed bridge in the case of different seismic wave, different wave speed and different constraint system. Obtain the dynamic response acceleration result of the key point in the bridge expansion device to make preparations for the partial analysis;3.Take the origin model of bridge expansion device in Jiashao Bridge as plan1. Optimize the constraint region of box girder in plan1and take the optimized model as plan2. Analyze the self vibration characteristics of plan1and plan2;4.Exert the acceleration obtained from the analysis of the dynamic response of the four-tower cable-stayed bridge on the key point of plan1and plan2, analyze dynamic response of the partial model of plan1and plan2, conclude their weakness region. Compare the result of the dynamic response of plan1and plan2to verify if the optimization of plan2is reasonable.