Research On Dynamic Behaviour And Seismic Response Of Extradosed Cable-stayed Bridges

China is one of countries in which earthquakes take place frequently. Bridges, transportation hub, that once are destroyed in the earthquakes will cause the great financial damage. Changshan bridge in Changhai County, Liaoning Province is the first cable-stayed bridge cross-sea short-pylon in the cold region in the domestic, whose location is seismically, hence it is crucial to analyze the dynamic characteristics and seismic response of it. The main research contents of this thesis based on Changshan bridge are as follows:(1) Solid element and link element are adopt to whole bridge spatial finite element model according to the design of Changshan bridge. In addition, longitudinal prestressed reinforcement are built in Changshan Bridge by the programming of ANSYS Parametric Design Language, and a new type of connection of reinforced and concrete joints are proposed.(2) Investigating static and dynamic analysis of Changshan bridge which is in service stage was carried out. Displacement and the internal force response of each component are calculated and analyzed with different load conditions during service stage. The rigidity and strength of the bridge are evaluated on the basis of deformation and stress analysis of the girder, supporting tower and pier and so on.(3) In addition, The free vibration periods and modes of the bridge are also calculated and analyzed. On the basis of this, the seismic response spectrum analysis of cable stayed bridge is carried out. Four seismic input types are designed for researching on the effect of vertical earthquake on bridge structure according to the standard under the action of E1 and E2 earthquake.(4) Seismic response analysis of cable-stayed bridge is carried out by using El-Centro wave. The displacements and the time history curves of the key section under the condition of horizontal, single direction and combined earthquake are obtained, the results are analyzed and summarized. Finally, the time history analysis results are compared with the corresponding response spectrum analysis results to identify the advantages and disadvantages of these two outcomes in the dynamic analysis.