Research On The Seismic Response Characteristics And Failure Modes Of The Large-span Subway Station Without Columns On The Top Floor

With the development of the economy,Chinese subway construction has achieved rapid development,and Chinese has built a number of large-span subway stations without columns on the top floor.As a new type of subway station structure,the large-span subway station without columns on the top floor has a more complicated stress state under the action of the earthquake.This paper conducts research on the seismic calculation method,the influencing factors of seismic response characteristics and failure mechanism of the large-span subway station without columns on the top floor.The main research contents and results of this paper are as follows:(1)Based on the actual engineering,through time history analysis and two pseudo-static seismic calculation methods,the application of the seismic response analysis of the largespan subway station without columns on the top floor is studied.Taking the calculation results of dynamic time history analysis as the standard,the application of the reaction acceleration method and the reaction displacement method is studied by comparing the internal force and deformation of the structure.Through comparative analysis,it is shown that the error of the reaction acceleration method is smaller,and it is closer to the calculation result of the dynamic time history analysis,and it is safer than dynamic time history analysis.(2)Analyze their influence on the seismic response characteristics of the structure through different the height of the side wall of the large space without columns on the first underground floor,the ride span rations of the roof and the thickness of the covering soil.Through comparative analysis,it is concluded that the higher the height of the side wall of the large space without columns on the first underground floor,the greater the bending moment of the flexural members of the station structure;the smaller ride span rations of the roof,the greater the bending moment of the station roof,and the top of the side wall will bend.The greater the moment,the smaller the bending moment of other bending members;the greater the thickness of the overburden,the greater the bending moment of the structure’s bending members.Therefore,in the seismic design,the height of the side wall of the first underground floor should be reduced as much as possible,ride span rations of the roof should be increased,and the thickness of the covering soil should be reduced.(3)Through time history analysis,study the large-span subway station without columns on the top floor.The results show that plastic hinges appear in the middle plate of the structure first.As plastic hinges appear at the bottom of the side walls,the bottom of the center columns,the top and bottom plates also enter the plastic zone.By changing the size of the structure and the thickness of the overlying soil,the failure sequence of the structural members did not change.The greater the height of the height of the side wall of the large space without columns on the first underground floor,the smaller the limit elastic interlayer displacement angle and the plastic interlayer displacement angle of the structure;the smaller the ride span rations of the roof,the larger the limit elastic interlayer displacement angle and the plastic interlayer displacement angle of the structure;The greater the thickness of the overburden,the smaller the ultimate elastic displacement angle and plastic displacement angle of the structure.Among them,this paper calculates that the limit interlayer displacement angle of the structure has a large difference in the specification,indicating that for this special subway station structure,the limit elastic inter-layer displacement angle and the plastic displacement angle cannot be simply applied to the specifications,and further research should be done.