Seismic Response Analysis Of Isolated Continuous Bridge Using Different Seismic Isolation Schemes

This dissertation takes a continuous bridge using isolation bearings as a practical example. Seismic response analyses of isolated bridges using different seismic isolation schemes are conducted. The research is proposed for engineering design guidance. The main work is as follows:(1) Ordinary spherical steel bearings, pot rubber bearings, lead core rubber bearings and nonlinear damping spoke shock isolation supports are analyzed. The dissertation includes the structure forms, working principles and mechanical model of the bearings. The equivalent linearization analytical model of nonlinear damping spoke shock isolation supports is proposed.(2) Finite element models of isolated continuous bridges are established. Seismic response analyses of the bridges are conducted using dynamic time history analysis method. The research includes the responses of shear force and bending moment at the pier foot, beam displacement and displacement of pier top. The results show that the natural vibration periods of the bridge are effectively enlarged. Meanwhile, the displacements of bridges are enlarged. Internal forces of the bridge are reduced. The isolation bearings can effectively reduce the ductility demand of bridge piers and alleviate seismic action of bridge structures.(3) Pile foundation is used in the bridge engineering. Soil medium has impact on seismic responses of the bridge structure through the pile foundation. The soil-structure interaction(SSI) has been considered according to Chinese codes. Seismic response analyses of the bridge with SSI are carried on. The result shows that soil-structure interaction reduces seismic responses of bridge structures with a longer natural vibration period. The efficiency of bridge design could be improved while taking SSI into consideration.