Seismic Vulnerability Analysis Of Assembled Subway Underground Station Structure

Prefabricated structure conforms to the development trend of modern architecture and is one of the important directions of building structure development in China in the future.For prefabricated subway station underground structure,the seismic performance in addition to related to its own characteristics,also is closely related to the site conditions and seismic characteristics,differences between the ground motion and ground will lead to the underground station structure appeared different degree of damage,and at present for prefabricated underground subway station structure seismic vulnerability research is less.Therefore,this paper takes Jin’anqiao telescope-connected prefabricated subway station as the research object,compares and analyzes the difference of seismic vulnerability of the prefabricated station structure caused by different types of ground vibration and different sites,and evaluates its seismic performance.The main research contents are as follows:（1）Select near-field pulsed ground motion,far-field long-period ground motion and ordinary ground motion,and compare and analyze the amplitude,duration,spectrum and other characteristics of the three different types of ground motion selected from the three elements of ground motion.The results show that the mean values of PGA,PGV and PGD of near-field pulsetype ground motions are the largest,while the mean values of PGV/PGA and PGD/PGA of farfield long-period ground motions are the largest and their duration is longer.Compared with ordinary ground motions,near-field pulsed ground motions and far-field long-period ground motions have more concentrated Fourier spectrum distribution and richer low-frequency components.（2）Based on the established finite element model of the soil-prefabricated subway underground station structure,the seismic response of the prefabricated subway underground station structure is studied by dynamic elastoplastic time-history analysis method.The results show that there is a large stress concentration in the joint area of the assembled station structure,and the Mises stress value is the largest in the joint area at the bottom of the side wall.In terms of structural damage,rigid domain is formed in the sleeve area of the structure under the action of earthquake,so that the damage position of the station structure is mainly concentrated at the end of the sleeve connection area,in which the middle column of the station is damaged first,which is the most unfavorable part of the assembled subway station.（3）Based on the incremental dynamic analysis（IDA）method,the maximum interstory displacement Angle of the station structure was taken as the damage index,and PGA was taken as the ground motion intensity index,and the difference of seismic vulnerability of the assembled station structure under three different types of ground motion was comparatively studied.The seismic vulnerability curve of the structure is drawn based on probabilistic demand model,and the failure state probability and vulnerability index are introduced to evaluate its seismic performance.The results show that the station structure has the highest probability of exceeding the corresponding performance level and the largest vulnerability index under the action of nearfield pulse-type ground motion and far-field long-period ground motion.（4）The influence of different types of ground motion on seismic performance of assembled subway underground station structure under different site conditions is studied.The results show that the softer the soil,the weaker the seismic performance of the station structure.Under different site conditions,the near field pulse ground motion and the far field long period ground motion both show stronger destructiveness.The damage potential of near-field pulsed ground motion is stronger with the increase of ground motion intensity in class ⅱ site,while the damage potential of far-field long-period ground motion is more obvious in class ⅲ site.Therefore,the influence of these two kinds of special ground motions on the seismic performance of assembled subway station structures should be considered in the seismic design.