Influence Of Soil-Structure Dynamic Interaction On The Bridge Isolation System

Currently base isolation is widely used as an effective vibration control method inarchitectural engineering field, and the theory based on the isolation are more mature.But most of the existing theories in use for isolation are based on the rigid foundationassumptions and ignore soil-structure interaction. This paper focus on this point,calculating and analyzing response of a structure with laminated rubber bearings,considered soil-structure interaction, and provide some beneficial results.This paper reviews the research profile of base isolation. Then focuses on the needfor the consideration of soil-structure interaction analysis on the isolation structure andthe study on the influence of soil-structure interaction of base isolation. On the basis ofthe above, Detailed introduces the lead-rubber bearing’s basic features, analysis methodand the foundation model commonly used, summarizes the mechanical models and theconclusion have been used in previous studies. Finally establish foundation-isolationstructure mechanics model.On the basis of theoretical analysis, use finite element modeling software ANSYSto simulate. Selects a lead-rubber bearings installed three-span continuous box girderbridge structure. Comparison and analysis of the three calculation models include thenon-isolated structure model not considering the soil-structure interaction, the isolatedstructure model not considering the soil-structure interaction, the isolated structuremodel considering the soil-structure interaction. Input the TianJin wave in the dynamictime-history analysis, then analyses and compare the dynamic response, get theinfluence on the lead rubber bearing isolation effect caused by soil-structureinteraction. Through the analysis get the following conclusions:(1)Foundation soil can filter out the high frequency waves and change the dynamicresponse of the structure.(2)Isolation system frequency is significantly less than non-isolation system,system become soft. Considering the soil-structure interaction, isolation systemfrequency further reduce. The lead-rubber bearings can extend the structure of thecycle, consume the seismic energy, effectively reduce the pier top displacement, theincreased displacement of the beam, but still manageable. (3)Considering the soil-structure interaction, the pier top of displacement, pier atthe end of shear and bending moment at the end of pier have Increased. Foundation soilinfluences the lead-rubber bearing isolation effect. Foundation soil is not simply theabsorption of seismic waves, but the impact on the structure of complexThus verify the soil-structure interaction on the effect of base isolation and thenecessity for its consideration.