Research On The Disperation Seismic Design Of Multi-span Continuous Bridge

Multi-span continuous girder bridge is the main type when crossing the wide valley of the river with the characteristics of reasonable load transfer, simple structures and easilyconstruction. Usually only one fixed pier is set on the multi-span continuous girder bridges, as for the other movable piers, the movable supports with little fiction bearing capacity are adopted. Most of the horizontal inertia force is beard by the fixed pie. As for the big mass of the multi-span continuous girder bridge,the seismic performance of the fixed pier becomes more important. In order to reduce the bearing force of the fixed pier, the desperation seismic design method is indispensable. Based on the seismic design of the components of bridges, the desperation devices with energy dispersion components and stiffness components are put forwardto reduce the seismic response of the fixed pier.The main research contents are as follows.(1) Introduce the dispersionseismic devices including the energy dissipation devices and the Stiffness devices of the multi-span continuous girder bridge. The main function of the energy dissipation devices is to redistribution the seismic force, whilethe function of the Stiffness devices is to restrict the displacement of the girder. The indoor model test is performed to analysis the desperation effect and failure mechanism of two different devices.(2) Establish the Pier and beam connection model with the interaction of the friction effect at movable supports and the dispersion seismic devices considered. Both of the nonlinear of the friction effect at movable supports and the dispersion seismic devices is incorporated to analysis the State process of the connection between the Pier and beam during the earthquake function. Then put forward a simplified finite element model.(3) A more comprehensive finite element model of the whole structure incorporating the nonlinear of the friction effect at movable supports and the dispersion seismic devices is established and the non-time history analysis is performed to analysis the inner force, displacement, curvature of the bottom pier. The results indicate that seismic devices can effectively increase the seismic force ratio beard by the movable piers and reduce the seismic response of the fixed pier. Compared the results with that of the model adopting lock-up device, it is concluded that in some case as the lockup device change the structural system, this model may loss its function of Energy Dissipation Capacity and can increase the input of the seismic function. These results indicate that in certain case, the dispersionseismic devices can more effective than the lock-up device.