Seismic Response Analysis Of High-rise Concrete Base Isolated Frame Shear Wall Structure

In recent years,with the rapid development of urbanization in China,the number of residential buildings and commercial office buildings has been increasing rapidly and their structural forms are becoming more diversified.As Chinese urban scales expanding and its urban population centralization,enough alert and preparations should be made with so many cities located near the seismic belt and fault.If earthquake occurs in densely populated areas,earthquake disasters will cause serious damage to urban infrastructure in these regions.This may cause a large number of casualties and loss of property,resulting serious social and economic impact.In view of serious damage of earthquakes,researchers in various countries have done a lot of research on earthquake prediction and defense.In recent decades,seismic isolation technology has been applied widely because of its superior performance.Compared with the traditional anti-seismic structures,seismic isolation technology can concentrate the deformation and energy on the isolation layers effectievly.This can seperate the ground vibration and superstructures,greatly reducing earthquake damage to bulidings.With the deepening of research and practice,seismic isolation technology will be applied to the high-rise buildings more and more widely.In order to promote the development of high-rise isolated bulidings further,the following aspects are studied for high-rise isolated frame and shear wall structures.First the seismic isolation design of a typical high-rise frame and shear wall structure under the 8 degree fortification intensity is carried out.And the isolation performance of isolated structure under rare earthqueke is cheaked.It is calculated that the horizontal seismic decrease coefficient of the isolated structure is 0.37 under the action of fortified earthquake.Under the action of rare earthquakes,the ultimate horizontal displacements of the isolation layers and the ultimate tension-compression stress of the isolation layer meet the requirements of codes.The isolation structure shows good working performance.Secondly,corresponding researchs on the overturning problems of high-rise isolated buildings under earthquake action is carried out.According to the high-rise isolated shear wall structure designed before,the prototype structure is simplified reasonably and the rigid body model with large aspect ratio is made.A series of shaking table tests under sinusoidal wave are carried out to explore the overturning response of the prototype structure.The research shows that the static overturning critical acceleration is conservative as a criterion for overturning of rigid body under the action of dynamic loads.And the overturning response of model increases with the increasing of the shaking table amplitudes.Thirdly,under the action of rare earthquakes,the superstructure of high-rise isolated frame shear wall structures may enter the plastic state.As for this problem,elastoplastic model of prototype structure has been established and analysed with the method of incremental dynamic time history analysis(IDA).The analysis results show that the maximum story drify angle occurs at the first floor of superstructures under the action of rare earthquakes and super strong earthquakes.The development order of structural plasticity is superstructure coupling beams,shear walls and frames.After the yielding of the shear walls at the first floor of superstructure,the plasticity of shear walls gradually develops upward along the floor.Besides,as the peak acceleration of ground increases,the failure mode of structure is mainly controlled by the overlimit of tensile stress of isolation bearings.Fourthly,according to the results of IDA analysis,the quasi-static analysis is carried out with finite element entity models from one frame of isolated and non-isolated prototype structures.The substructure contains the seismic isolation layer and the bottom two layers of the prototype structures.By comparing the calculated results,it can be found that there are differences in plastic development and damage modes between isolated and non-isolated substructures.The calculation results with different linear stiffness and reinforcement ratio of transfer beam in isolated substructures shows improving the two parameters mentioned above can reduce the damage and improve the ultimate bearing capacity of substructures.Finally,suggestions on the reasonable value of linear stiffness and reinforcement ratio to the isolated substructures has been made.