Analysis Of Seismic Response Of Bifunctional Damping Masonry Structure Of Bottom Frame

In order to improve the seismic performance of masonry building with bottom frame,on the basis of previous studies,a viscous damper is added to the bottom frame layer,and the isolation layer is added between bottom frame and upper masonry structure,from which bifunctional damping masonry structure of bottom frame are formed in this paper.The seismic response of the bottom frame is reduced by means of dampers and isolators,and the seismic action of the upper masonry structure is also reduced by the isolation of earthquake excitation to the upper masonry structure,achieving the purpose of the structure damping.In order to explore the performance of bifunction damping masonry structure of bottom frame subjecting to seismic action,the research of the reasonable value of damping parameters are firstly carried out in this paper;then,the finite element software SAP2000 is used to analyze the dynamic time history of the structure and the corresponding seismic structure applying to unidirection and bidirection seismal action;finally,the influence of the increase of the number of layers of the bottom frame on the seismic performance of the structure is investigated.The main work of this paper is as follows:(1)Based on random vibration theory,the MATLAB R2014 a can be used to analyze nonlinear function of multi-parameter.The minimum response variance of structural displacement of upper and lower structure for the single frame of bifunctional damping masonry structure of bottom frame are analyzed.The analysis results indicate that equivalent damping ratio of bottom frame,damping ratio of the isolation layer,natural vibration frequency ratio and the mass ratio of the upper and lower structures,which all has a great influence on the two minimum response variance,and the parameters also affect each other.Therefore,it is necessary to comprehensively analyze the parameters of the structure.It is suggested that equivalent damping ratio of bottom frame should be about 0.30,and damping ratio of the isolation layer should be between 0.20?0.40,and natural frequency ratio of the upper and lower structures should not exceed 1.0.(2)The method of state equation direct integration,the finite element software SAP2000 and the forced decoupling method are used to analyze the unidirection seismic response of the structure,the corresponding seismic structures are also analyzed by the SAP2000 software.The results indicate that the results of state equation direct integration are well consistent with the results of finite element software SAP2000.The forced decoupling method has better accuracy in solving the low order vibration of the structure,but the error is too large for higher order vibration.(3)The three-dimensional analysis model of traditional bottom frame masonry structure and bifunctional damping masonry structure of bottom frame is established.In view of four sites,the seismic response of two structures under the bidirection earthquake action is compared and analyzed.The results indicate that the seismic performance of bifunctional damping masonry structure of bottom frame is better than that of the traditional structure.(4)On the situation of the bottom frame with two layers,three layers,and four layers,the effect of the increase of the number of layers of the bottom frame on the seismic response of the structure is investigated on ?,? and ? sites.Analytical results indicate that the number of floors of the bifunctional damping masonry structure of bottom frame may be designed to three floors.