Seismic Response Analysis And Isolated Measure Research Of Long-Span Cable-Stayed Bridges

The bridge, as well as the key facility in highway and railway traffic system, is the vital element of transportation lifeline. The earthquake is one of the devastating natural disasters that always cause tremendous damage to humanity. A lot of bridges are destroyed during the violent earthquakes, which not only directly caused economic losses, but also greatly affected earthquake relief work and the production resumption.For these sea-crossing bridges built in deep water, it is necessary to research on pile coupling effect of water. Generally, the coupling effect of water and structure appeared in hydrodynamic mass and hydrodynamic damping. The finite element code ANSYS is employed to build model for a cable-stayed bridge where the interaction of pier, water, and structure is considered. Time-history analysis and response spectrum analysis for this cable-stayed bridge are discussed. Correspondingly, hydrodynamic effects on dynamic response of bridge structures are calculated.In this thesis it is given a systematic study on large span cable-stayed bridge consist of pile-water coupled response, non-uniform excitation seismic response analysis and design of viscous damper. The main job includes the following:1) The thesis summarizes the static method, response spectrum analysis and time history analysis method of calculation methods as well as the advantages and disadvantages of them. Moreover, the fluid-structure interaction equation and pile-soil interaction equation are also discussed.2) The seismic response for the high-pier large-span cable-stayed bridge is calculated. In the finite element model, the method of hydrodynamic mass and damping are used to take the interaction of water and structure into account. To analyze the effect of hydrodynamic damping and hydrodynamic mass on the bridge structure, the time-history seismic response of bridge is calculated under the following conditions respectively:considering hydrodynamic mass and hydrodynamic damping, considering hydrodynamic mass but without hydrodynamic damping, considering neither hydrodynamic mass nor hydrodynamic damping. The results show that hydrodynamic mass has an obvious influence on the internal forces of the main tower of cable-stayed bridge because of its magnifying effect for the shear and moment of the bottom of the tower, inversely hydrodynamic damping has not.3) The traveling wave effect and irrelevant effect on the seismic response of long span cable-stayed bridge are analyzed in detail and some results about the multi-support excitation are obtained. 4) The installation of viscous dampers can reduce the vibration responses of the long-span bridge and won't increase the stiffness of the structure. So it is an ideal vibration damping technique for the long-span bridge.