Seismic Response And Simplified Mechanical Model Of The System Of Subway Station With Upper Frame Structure

Rail transit subway station and its upper structure are new structures integrating transportation,office,shopping mall,residence and other functions.The emergence of this structure makes the subway station and surrounding buildings realize integrated construction.As the urban rail transit subway stations and their overlaying structures have emerged in large numbers in recent years,and such structural systems often use large-span,high-rise box-type metro stations as large platforms,and small-span and low-rise frame structure arranged on the large platform as upper structure.As a result,a wide range of vertical component of discontinuous phenomenon appears,which is particularly detrimental to its own seismic safety.In this paper,numerical analysis is used to analyze the seismic response law and influence factors of the large-chassis subway station and its upper-cover frame structure system.Then based on the basic principle of traditional response acceleration method,a mode decomposition method-response acceleration method for seismic analysis of ground and underground integrated structure system is put forward.The main work and conclusions are as follows:(1)A three-dimensional finite element model of the metro station with large chassis and its single tower frame structure system on the roof was established to analyze its seismic response law.The dynamic response of metro station with large chassis and its upper frame structure system was analyzed from five aspects: different upper cover layers,upper cover structure bias,different thickness of transfer plate,seismic waves with different spectral characteristics,and single-directional and double-directional ground motion input.The results show that the existence of the upper frame structure increases the internal force of subway station structure,and the more the number of floors of the upper structure,the greater the increase of internal force.In this structural system,the underground structure of subway is still in shear deformation under the action of earthquake,and the existence of the upper structure only changes its relative displacement peak value,but not its deformation mode.The variation of the number of upper layers and the thickness of the transfer plate will not cause the change of the internal force trend of the underground subway structure.The change of the position of the upper cover structure has an effect on the amplitude and variation of internal force.The change of the number of layers,the position and the thickness of the transfer plate has little influence on the response of the displacement and acceleration of underground structure.(2)A three-dimensional finite element model of the frame structure system of the metro station with large chassis and double-tower structure with the upper cover was established to carry out dynamic time-history analysis.And the effect of double-tower structure with the upper cover on the seismic response of metro station with large chassis was studied.The results show that,compared with the single-tower structure with the upper cover,the column bending moment and peak acceleration response of the underground structure is obviously reduced by the double-tower frame structure with the upper cover.The maximum bending moment response of the side wall of subway station structure is located in the bottom area,and mid-value located in the top area,and the minimum located in the middle area.(3)Based on a series of numerical models of dynamic interaction of soil-metro station and its upper frame structure system,the influence law of upper frame structure on seismic response of metro station with large chassis was obtained.Meanwhile,according to the traditional response acceleration method for seismic calculation of underground structure,a mode decomposition method-response acceleration method was proposed for seismic analysis of overground and underground integrated structural systems.Taking a subway station and the upper cover high-rise building integration project in Beijing as engineering background,the applicability of the mode decomposition method-response acceleration method was analyzed compared with traditional time history method and response acceleration method under the influence factors of peak acceleration,structure rigidity,soil stiffness,number of stories of upper structure and seismic wave types.The results show that the proposed method is a simple,accurate and safe method,which can be used in seismic calculation of similar projects.