Research On The Seismic Respanse Of Story Isolation Buildings Under Near-fault Ground Motions

With the rapid development of isolation theory and isolation technology,A large number of isolated buildings came into being and have been proved to be effective in reducing the impact of earthquakes on buildings.However,the domestic and foreign scholars on the investigation and Research on the earthquake disaster,near fault earthquake is significantly different from the far field characteristics of earthquake,Such as short duration,large velocity pulse and high power make the isolated structures in near fault earthquake and far-field earthquakes of different dynamic response.Therefore,in order to promote the application of seismic isolation technology in building,the dynamic response of the isolated structure under near fault earthquake must be further studied.In this paper,a comprehensive study of the two aspects of the isolated structure and the near fault earthquake is carried out.Using the finite element software SAP2000 to establish 6 two storey steel frame structure model,Natural rubber bearing and lead rubber bearing are used as isolation device respectively.157 near fault ground motion records are selected from the Pacific Earthquake Engineering Research Center.According to the 3 criteria(different fault rupture direction,different types of site,whether it contains pulse)157 near-fault seismic records are input to two steel frame isolated structure model,The dynamic response of two kinds of bearing isolated structures are calculated respectively,and the influence of different kinds of near fault ground motion records on the dynamic response of the isolated structure is analyzed.Then selecting 8 characterization of near fault ground motion characteristics parameters,according to the principle of correlation analysis,analysis of the correlation between the 8 parameters and the corresponding dynamic structure parameters by using the SPSS statistical analysis software.According to the seismic recording of the three kinds of classification standard(different fault rupture direction,different site class,whether it contains pulse)use SAP2000 to isolated structure input energy,hysteretic energy and damping energy dissipation and energy distribution for further analysis.The main results of this thesis are as follows:(1)Dynamic response of different isolation structures under near fault earthquake action is different.(2)Different types of near fault ground motion records are different,the location of the isolation device is different,and the correlation between the characteristic parameters of ground motion and dynamic response of the structure is different.Therefore,seismic isolation structure design should be designed according to the characteristics of ground motion records,the dynamic response of isolated structure,property isolation device,the location of the isolation layer into account.(3)Isolated Structure input energy as the ground motion recorded different fault rupture direction,different site conditions,whether it contains the pulse change and other factors are different,wherein the input energy: FN direction seismic waves more than FP direction seismic waves,Ⅲ class site> Ⅱ class site >Ⅰclass site,a pulse of seismic waves is significantly greater than the pulse-free seismic wave.The hysteretic energy dissipation ratios and the damping energy dissipation ratios increases toward the isolation layer varies.The result of this study provides reference bases for Ground motion records selected the location and properties of the seismic isolation device selected the destructive potential of ground motion assessment analysis.The hysteretic energy dissipation ratio increases first and then decreases with the increase of the position of the isolation layer,The damping energy dissipation ratio decreases first and then increases with the increase of the position of the isolation layer.