Time History Analysis On Eccentric Torsion Effect Of Base Isolation Structure Under Bi-directional Horizonal Earthquake

Basic earthquake isolation belong to the passive control of engineering structure vibration control system, has developed rapidly in recent years. Different from general aseismic structure, base isolation structure form its isolation layer by seting sliding support between the upper structure and foundation. When the earthquake effecting on, the isolation layer produces sliding displacement,then part of seismic energy that passing to the upper structure is consumed, in turn, achieving the isolation effect. Research results and a series of strong earthquake observation records at home and abroad show that isolation structure not only holds obvious isolation effect, at the same time, its construction is convenient and it is economic and secure.On the theoretical analysis, base isolation structure analyzes seismic response usually by shaking table test and finite element software these two forms. This paper is to use Friction pendulum vibration isolation units (Friction Isolator) in SAP2000finite element software to simulate earthquake isolation bearing, then according to different analysis purposes, establishing different base isolation structure model. Based on the basic analysis method of time history analysis method, using different eccentric layout scheme, this article establishes different base isolation structure finite element model with the eccentricity of0,0.05,0.10,0.15,0.20,0.25and0.30respectively, then to analysis the influence of Bi-directional horizontal seismic action to of base isolation structure effect and eccentricity on the structural torsional effect. Results indicate that support displacement under bi-directional horizontal seismic action is bigger than that under one-way horizontal seismic action, acceleration, displacement and torsion effect increases with eccentricity. Therefore, it is necessary to consider bi-directional seismic action, meanwhile controlling the eccentricity of the structure in practical engineering.