Application Of Seismic Isolation Technology In Seismic Strengthening Of Over Limit Bottom Frame Masonry Structure

From the earthquake disaster in recent years,the damage of the bottom frame masonry structure in the earthquake is particularly serious,the safety of the people’s life and property is also not guaranteed because of the destruction of the bottom frame masonry structure,and the property loss is serious.Since the 90 s of last century,with the accelerating process of urbanization in China,a large number of rural population has poured into cities and towns,and the demand for the bottom and upper residences is increasing.A large number of bottom frame layers,the number of upper masonry or the total height of the building exceed the standard requirements of the over standard bottom frame masonry structure.House 。 Because most of the bottom frame of this kind of building has not set Anti-seismic wall according to the standard or set a small number of Anti-seismic wall,the structure is “soft and rigid”,the seismic performance of the structure is greatly reduced,and there is a serious safety hazard.Therefore,the seismic performance of this kind of structure is analyzed,and reasonable reinforcement plan is urgent based on the analysis results.At present,mature housing structure reinforcement methods include enlarging section method,outlining steel method,externally bonded steel method,externally sticking carbon fiber method and adding steel support.However,the above reinforcement methods generally need to make great changes to the structural components of the original structure,which has the problems of long construction period,unused construction process and high comprehensive cost of strengthening.With the growing maturity of isolation technology and the popularization and application of isolation bearings,seismic isolation technology has gradually become a new reinforcement method for existing structures.In this paper,through the finite element simulation analysis of a certain over limit bottom frame masonry structure,the application of isolation technology in the reinforcement of this type of building is explored,and the seismic performance of the structure after isolation and reinforcement is analyzed.Based on the field investigation data and the original design drawings,the analysis model is set up.By using the SAP2000 finite element analysis software,the linear time history analysis and nonlinear time history analysis are carried out under the action of EL-Centro seismic wave,Tangshan seismic wave and synthetic seismic wave,and the weak link of this type of structure is found out.The basic cycle of the structure is simply derived.Combined with the principle of structural isolation,the Over limited bottom frame masonry structure with insufficient seismic resistance is treated with two reinforcement methods,basic isolation and interlayer isolation,and the seismic response of the reinforced structure is calculated.The results show that the structure’s period can be extended after the earthquake isolation,the acceleration of the structure,the interlayer displacement,and the interlayer position of the structure are extended.The moving angle and seismic shear force are all controlled effectively,and the energy dissipation performance of the isolation bearing is good.This paper studies the problem of the isolation layer in the upper part of the overlying bottom frame masonry structure with the number of stories above one level,two storeys and three storeys.By comparing the seismic responses of the structure before and after isolation,it is obtained that the adjustment of the acceleration of the structure below the isolation layer is better than the interlayer isolation,but the adjustment of the inter layer displacement of the structure below the isolation layer is just the opposite,so it is more appropriate to adopt the base isolation to reinforce the above over limit structure.