Study On Seismic Behavior Of Foundation Isolation In Frame-shear Structure

The isolation technology is a new type of seismic method.The base isolation is a kind of isolation technology.Its construction is simple and fast,and the technology is relatively mature.The basic idea of base isolation is to set up a special layer of isolation between the building and the basis of the foundation,because the seismic waves are transmitted to the building through the basis of the foundation in the form of energy.The base isolation layer can block the transmission of seismic energy to the upper building,it can effectively reducing the sloshing of the building and reducing the response of the earthquake.In recent decades,the basic isolation technology has made significant progress in the shock absorption effect,and more and more researchers have increased their research in this area.In this paper,by referring to the seismic related literature,using the ETABS software to establish the frame shear wall model,arranging the base isolation bearing,establishing the non-isolated structure model,the lead isolation structure model and the mixed isolation model,modal analysis,time history analysis under seismic conditions and structural check calculation under rare earthquake conditions are performed.And the author studies the periodic changes,Interlaminar shear forces and overturning moment changes under three models,and then observes maximum influence coefficient and damping coefficient of horizontal earthquake.The numerical value of the coefficient can be used to analyze the shock absorption effect of the isolation model,and then study the layer displacement change and the top layer acceleration variation,and check the bearing capacity,bearing displacement and anti-overturning moment under rare earthquake conditions.The main conclusions obtained are as follows:(1)Since the processing of the base isolation weakens the transmission of the seismic energy to the upper part of the structure,the two isolated structure models are significantly longer than the non-isolated structure model.(2)Under the same seismic wave condition,the inter-layer shear force,overturning moment,layer displacement and top layer acceleration of the two isolated structure are greatly reduced,which proves that the building structure has a very obvious reduction after isolation processing.(3)The horizontal damping coefficient of the two isolated structures is less than 0.40,and the horizontal seismic influence coefficient drops below 0.08.In addition,the mixed isolation structure has better damping effect than the lead isolation structure.According to the specification requirements,the upper structure can be calculated according to the isolation,and the theoretical default horizontal seismic action is reduced by one degree.(4)Under the rare earthquake conditions,the bearing capacity and maximum compressive stress of the base isolation bearing should meet the requirements of the specification.The displacement of the bearing is less than the 0.55 D and 3 times thickness than the total internal rubber,and the factor of safety against overturning is greater than 1.2,meeting the requirements of the specification.