The Seismic Performance Analysis And Reinforcement Study Of Masonry Structure With Frame And Seismic-Wall In The Lower Stories Beyond Code Limits

Due to its good function,relatively low construction cost and simple construction,the masonry structure with frame and seismic-wall in the lower stories has been widely used in the central and western regions of China,and a considerable number of such buildings that were built at the end of the last century and the beginning of this century are still in service.However,this type of structure has a structure character of “the above stiffness is bigger than underside”,“the above weight is heavier than underside” and has poor seismic performance.In some areas where seismic precautionary intensity is low,the construction habit of “emphasis on bearing capacity and despising seimsic capacity” has always been the norm,the number of stories of masonry structure with frame and seismic-wall in the lower stories frequently went beyond code limits.In the latest revision of 2016,the Code for seismic design of buildings increased the seismic precautionary intensity in some regions.There is a doubt that whether these masonry structure with frame and seismic-wall in the lower stories beyond code limits could meet the seismic precautionary requirements.Therefore,it is very necessary and urgent to analyze the seismic performance and research the reinforcement methods of these masonry structure with frame and seismic-wall in the lower stories beyond code limits.Based on previous researches,the finite element numerical simulation analysis of the seismic response for masonry structure with frame and seismic-wall in the lower stories under the frequent earthquake and rare earthquake was carried out by using the SAP2000 software.Specific work is as follows:(1)In this paper,the establishment of the finite eleme nt model in the analysis software,the selection of constitutive relations and the input of seismic waves for the masonry structure with frame and seismic-wall in the lower stories are studied.(2)According to the practical engineering,this paper sets up the masonry structure with frame and seismic-wall in the lower stories beyond code limits finite element model.By adding the number of bottom frame and seismic-wall stories,the number of upper masonry stories,and adding the number of both stories,the effect of the number of stories beyond code limits on the seismic performance of the structure is studied.The results show that adding 1-3 stories of the bottom frame and seismic-wall has a positive effect on the seismic performance of the structure under frequent earthquakes,three kinds of beyond code limits in the story under the action of rare earthquake will reduce the seismic performance of the structure.(3)Four reinforcement methods are adopted to reinforce and analyze an existing masonry structure with frame and seismic-wall in the lower stories beyond code limits in this paper.It is found that the reinforcement method of alter structural system is the best.The reinforcement method of widening the section size of the frame beam is not desirable in the masonry structure with frame and seismic-wall in the lower stories.