Study On Theory Of Performance-Based Seismic Design To Over-Track High-Rise Structures On Metro Depot

The rapid increase of urban population in China has greatly promoted the planning and construction of public transport represented by metro.As an important part and basic production unit of the metro system,the number of metro depot is also increasing year by year.In order to deal with the waste of urban land resources caused by the low land utilization rate of traditional metro depot,the over-track high-rise project came into being and flourished.Due to the limitation of track line and the demand of superstructure,the over-track high-rise structure on metro depot usually has transfer story,and the frame supported story has no landing shear wall.It is a vertical irregular structure,and its seismic performance should be paid attention to.China is located in the two most active earthquake zones in the world,and earthquake disasters occur frequently.Previous major earthquakes have caused serious economic losses and huge casualties,and constantly remind people to pay attention to the research on the seismic performance of structures.Therefore,it is of great significance to study the seismic performance of over-track high-rise structures on metro depot,which is related to the national economy and the people’s livelihood.Based on the above background,this thesis intends to conduct a large number of finite element analysis on the seismic performance of the over-track high-rise structures on the metro depot,evaluate the seismic performance of the over-track high-rise structures on the metro depot under seldom occurred earthquake,and explore the influencing factors of the seismic performance of the over-track high-rise structures on the metro depot;The performance level division and performance index limit applicable to the over-track high-rise structures on the metro depot are put forward;According to the proposed performance level division and performance index limit,the vulnerability function of the over-track high-rise structures on the metro depot is established,and the seismic performance of the over-track high-rise structures on the metro depot is evaluated from the perspective of vulnerability.The specific research contents are as follows:Based on the practical engineering case of over-track high-rise structure on the Nanjing Qixia Mountain metro depot,6 analysis models of over-track high-rise structure on metro depot are designed by using YJK building structure design software(hereinafter referred to as YJK software),which are divided into two groups A and B;Among them,the variable parameter of group A model is the axial compression ratio of frame-supporting column,and the variable parameter of group B model is the section measurement of transfer beam;According to the design results of YJK software,the elastic-plastic analysis model of Open Sees software is established;The reliability of Open Sees analysis model is verified by comparing the periods of the model.7 seismic waves(5 natural waves and 2 artificial waves)are selected to carry out inelastic time history analysis of the structure under seldom occurred earthquake;The influence of the axial compression ratio of frame-supporting column and the section measurement of transfer beam on the seismic performance of the over-track high-rise structure on metro depot under seldom occurred earthquake is studied;The results show that the axial compression ratio of frame-supporting column has a great influence on the seismic performance of the over-track high-rise structure on metro depot;The section measurement of the transfer beam has no significant effect on the seismic performance of the over-track high-rise structure on metro depot,and the section measurement of the transfer beam should be controlled by its shear capacity.Using YJK software,by changing the design parameters such as the clear distance of shear wall,the thickness of shear wall and the length of wall limb,the analysis models of 36 overtrack high-rise structures on metro depot are designed and transformed into Open Sees analysis model;3 endurance time acceleration functions are synthesized,36 structural analysis models are analyzed,and the performance level division and performance index limit suitable for the over-track high-rise structures on metro depot are put forward;The performance level of the over-track high-rise structures on metro depot is divided into four levels: "slight damage","medium damage","serious damage" and "collapse",and the corresponding performance index(inter story displacement angle)limits are given,which are 1/434(slight damage),1/176(medium damage),1/117(serious damage)and 1/88(collapse).The seismic vulnerability analysis of group A model is carried out,and the demand model and vulnerability function of group A models are established;The results of vulnerability analysis show tha: The transcendental probability of collapse performance state level under seldom occurred earthquake in degree 7 seismic fortification zone is between 6%～7%,which meets the requirement of "no collapse under seldom occurred earthquake";The influence of axial compression ratio of frame strut on the exceedance probability of the whole structure is not significant;The axial compression ratio of frame-supporting column mainly affects the seismic response of the bottom and transfer story of the structure;Under the PGA value(0.22g)corresponding to the large earthquake in the seismic fortification intensity area of degree 7,the probability of the bottom and transfer story of group A structural analysis model exceeding the "serious damage" performance state and "collapse" performance state is basically 0,which can ensure good seismic performance.