| Longitudinal and transverse Seismic response of multi-span continuous girder bridge are different, which means that in the current state there is no seismic isolation device could reduce bidirectional seismic response simultaneously. Lead rubber bearing (LRB) has small horizontal resistance under creep loads, and its post-yield stiffness reduces quickly under seismic excitations, while the hysteretic behavior of lead core dissipates the seismic energy. Fluid viscous damper(FVD), which is a speed-related energy dissipation device, could provide strong resilience and excellent position-limiting capability. Using these two devices as a system could control seismic response of longitudinal and transverse effectively. On the basis of this idea, this study carried out a sort of investigations and main work are following:1. Taking a look back into design and calculation theory of bridge seismic engineering and investigating the seismic isolation theory, mechanical properties, applicative conditions and method of simulating in software of LRB and FVD.2. A finite element model of a five-span continuous girder bridge was set up via ANSYS and dynamical properties of this model were investigated.3. With the application of non-linear time history analysis, the seismic responses of this bridge were calculated and the effectiveness of LRB and FVD were studied by comparing the results of finite element analysis. Moreover, the effect of diameter of lead core was also studied in this paper.4. On the basis of energy analysis theory, the input energy of piers under earthquake excitation was calculated and the effectiveness of LRB and FVD on this issue was analized. Further, a safety factor of piers under earthquake based on energy method was calculated.5. A brake force experiment was also carried out and the experimental results were correspondent to theoretical result, which provides a verification of this seismic isolation technology. |
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