Research On The Seismic Performance Of Structures With Story Isolation Design For Metro Depot Cover

In order to alleviate the shortage of urban land and efficiently utilize land resources,it has become a trend to carry out property development on the platform of subway vehicle depots.Due to the different usage functions of the upper and lower structures of the subway’s upper cover structure,the problems such as discontinuous vertical components,vertical body retraction,and sudden changes in lateral stiffness have extremely adverse effects on seismic design.In high-intensity seismic areas,traditional seismic design methods are difficult to meet their seismic requirements.However,the application of interlayer isolation technology can solve the problem of sudden changes in vertical stiffness of building structures,while reducing the seismic response of the main structure,thereby improving its seismic performance.This article is based on the construction project of a subway vehicle depot in Xi’an,and establishes a finite element model to conduct elastic-plastic time history analysis on the interlayer isolation structure.It evaluates its seismic performance under earthquake action,analyzes the interaction between towers in the structure,and combines seismic vulnerability analysis to predict the exceedance probability of a single tower structure on the subway under different limit states.The specific work is as follows:(1)The study compared the dynamic characteristics of a three-dimensional finite element model with and without interlayer isolation using the OpenSees program.The interlayer isolation structure was verified to undergo elastic-plastic deformation during rare earthquakes,and the horizontal displacement as well as tensile and compressive stresses of the isolation layer were evaluated.The study found that interlayer isolation technology reduced the acceleration and displacement responses of the structure,In order to achieve a significant seismic reduction effect,after verification,all indicators of the structure meet the requirements of the specifications.(2)A time history analysis was conducted on the double tower and single tower structures with large chassis under rare earthquake action,and the variation laws of the period,internal force response,displacement response,and acceleration response of the two structures were obtained.The results indicate that the interaction between the towers exists,but the seismic response laws of the two structures are basically the same.Therefore,to improve efficiency,a single tower structure can be selected for analysis and research.(3)Seismic vulnerability analysis was performed on a single-tower interlayer isolation structure with a large base and its corresponding seismic-resistant structures using IDA method,and the seismic performance of the structure after the application of interlayer isolation technology was further evaluated.The results show that at all performance levels,the overall failure probability of interlayer isolation structures is much lower than that of seismic structures.Under earthquake action,The horizontal displacement exceeding the limit of the isolation support is the main failure mode of the interlayer isolation system.