Analysis Of Structural Vulnerability Of Subway Station Under The Action Of Horizontal And Vertical Ground Motion

The subway station considering the combined action of horizontal and vertical ground motion requires higher ductility and strength requirements than the action of horizontal ground motion.Therefore,the study of the joint action of horizontal and vertical ground motion is of great significance to the seismic design of subway stations.Taking a typical two-story three-span subway station as the research object,this paper studies that the most damaged component of the subway station is the bottom column.Based on the vulnerability analysis method,the vulnerability curves of subway stations under different directions of ground motion were compared.The vulnerability analysis of subway stations in soft soil area is carried out,and the vulnerability analysis of subway stations in different buried depths and soil conditions is carried out.Furthermore,the deformation-energy two-parameter damage model of subway stations in soft soil area under the joint action of horizontal and vertical ground motion is established.The main research conclusions are as follows:(1)According to the requirements of seismic response analysis and vulnerability analysis,the damage analysis of a typical two-story three-span subway station is carried out.It is found that the middle column of a subway station is the key part in seismic analysis,and the damage time-history relationship of dissipated energy index established can better reflect the damage of the structure.(2)The seismic vulnerability curve of subway station under the action of horizontal,vertical,the joint action of horizontal and vertical ground motion are established.Vertical ground motion has great destructive power,the subway station under the joint action of horizontal and vertical ground motion of the most serious seismic damage,the participation of the vertical ground motion makes vulnerability curve beyond the highest probability increased by about 50%;The existence of superstructure changes the failure mode of subway station and restrains the destructive power of vertical ground motion to subway station to a certain extent..(3)Based on the orthogonal test,the sensitivity of buried depth,soil quality and superstructure to the displacement response of subway station under the combined action of horizontal and vertical ground motion is analyzed.It is found that the influence of buried depth on the displacement response of subway station is highly significant,followed by soil quality,while the influence of superstructure on subway station is not significant.(4)The vulnerability analysis of subway stations in soft soil area under different directions of ground motion is carried out,and the vulnerability curve of subway stations and the evolution curve of earthquake probability density are established.With the increase of ground motion level,the damage range of subway stations under horizontal or vertical ground motion is mostly near the slight damage.Under the joint action of horizontal and vertical ground motion,the damage of subway station will gradually changed from slight damage to collapse damage.There is little difference in the vulnerability curves established by statistical or theoretical fitting methods.(5)The vulnerability of subway stations under different buried depths and soil conditions in different directions is studied.When the buried depth is shallow,the damage of subway stations is small and close to each other,and the damage degree of subway stations increases sharply with the increase of buried depth.When the soil changes from medium hard soil to soft soil or changes from medium hard soil to hard soil,the vulnerability curve of the subway station will show an upward trend.(6)Compared with the vulnerability curve of the deformation-energy two-parameter damage model and the one-parameter damage model under the combined action of horizontal and vertical ground motion,the vulnerability curve of the two-parameter damage model has a greater exceedance probability.