Analysis Of Seismic Response Of Shock-absorbing Structure With Friction Dampers In Bottom Frames

The bottom frame masonry structure building is widely used in China.However,the rigidity of the upper wall is large,and the lateral stiffness of the bottom frame is small,so the seismic performance is poor.This paper provide a method for setting that friction damp at the bottom frame and adding a vibration isolating layer between the top and bottom layer of the frame to achieve the effect of shock absorption.Because the isolation layer is set up at the bottom of masonry structure,eliminates the adverse effects of structural transition layer stiffness on the seismic response and improves the overall seismic capacity of the structure.The main work of this paper is as follows:(1)In order to analyze the seismic response of the structure under seismic excitation,this paper using state-equation direct integration method to solve the seismic response vibration equation for setting up a damping structure of the friction damper,and the result is in good agreement with the analysis results of the SAP2000 software.(2)In this paper,the practical calculation method of seismic action can be used to calculate the seismic action of the structure with friction dampers.The results show that the seismic response of the structure is much lower than the traditional structure.(3)In this paper,the forced decoupling method is used to analysis the structure,and the results are compared with the previous ones.The author has obtained that the deviation of the first and second order vibration response of the structure by the forced decoupling method is small,but the deviation of the higher vibration modes is large,and the damping effect of the structure is overestimated.(4)By using SAP2000,the author establishes the traditional bottom frame masonry structure model and the spatial model of the bottom frame bifunctional damping structure.Then the seismic responses of two structures under four different fields are analyzed.The results show that the dual-function seismic absorption structure of bottom frame has better performance.(5)For the case of two-story frame,three-story frame and four-story frame,the author studies the influence on the increase of the bottom frame layer on the seismic response on the site of Class I,Class II,III and Class IV.The results show that the number of layers at the bottom of the frame can be increased to four when the maximum acceleration of the earthquake is 70 Gal,and the number of layers should be increased to three when the maximum acceleration is 400 Gal.