Static Analysis And Seismic Response Mechanism Analysis Of Integrated Station-bridge Elevated Metro Station Structure

The integrated station-bridge elevated metro station structure is a new structure system which has developed rapidly in recent years.Because it involves two specialties of building structure and bridge structure,the static design method,failure mode and earthquake damage mechanism of this structure are still in the preliminary stage of study at home and abroad.With the increasing of rail transit engineering examples,the stress of the "station-bridge integration" Metro viaduct station is exerted.Behavior research is also imminent.Based on the Sandiancun Station Project of Xi'an Metro Line 5,the static and seismic responses of the "station-bridge integration" subway viaduct station are analyzed as follows:(1)The differences between building structure and bridge structure in design reference period,design load,load combination,design analysis method,crack calculation of concrete component,deformation calculation of concrete component and comparison of seismic acceleration response spectra are compared and analyzed.The reasonable engineering design method of this structure is summarized.It is concluded that the design and construction requirements of track girders and their supporting structures should be the same as those of interval bridges in the process of structural design of "station-bridge integration" Metro viaduct station,and the design and construction of other structural components should be carried out in accordance with the provisions of the code for structural design of buildings;and the seismic design of the station structure with three columns and above should be carried out in accordance with the current national seismic design code for building structures.(2)Based on the finite element software MIDAS/CIVIL,a three-dimensional finite element model is established to analyze the stress of the track beam.Referring to the provisions of the International Union of Railways(UIC)on the loading mode of continuous railway bridges and the provisions of China's "Code for Design of Railway Bridges and Culverts"(TB10002-2017)on the static and live load loading mode of trains,a comparative analysis is made on the track beam of this structure.The results show that the difference of mid-span displacement,mid-span bending moment and negative bending moment at support is less than 3% under the two loading modes.Considering that the loading mode of UIC is safe and easy to operate,it is suggested that similar structures can be loaded according to this mode.(3)The finite element model considering the interaction between pile and soil and the finite element model based on the assumption of rigid foundation are established respectively,and the natural vibration characteristics of the subway station structure are analyzed.The results show that the period of the structure considering the interaction between pile and soil increases and the flexibility of the structure increases,but the shape of the first 6 modes is the same as that based on the assumption of rigid foundation,The train load is applied to increase the structural period,and the increase ratio is within 1%.The train load has little influence on the structural period.MIDAS/GEN is used to establish the finite element model considering pile-soil interaction and the finite element model based on the assumption of rigid foundation.The results show that the maximum floor displacement of the structure considering the interaction between piles and soil increases and the base shear decreases,and the design method based on the assumption of rigid foundation is conservative in the analysis of earthquake response.The train load has a great influence on the stress of the supporting rail beam and column,and has little influence on the stress of other columns.However,in order to better conform to the engineering practice,it is recommended to consider the effect of the train load in the seismic response analysis of the same structure.(4)The stress condition of the structure under rare earthquake is analyzed.The development of plastic hinge under seismic wave is obtained,and the failure mode of the structure under rare earthquake is analyzed.Then,the seismic responses of structures considering pile-soil interaction and based on the assumption of rigid foundation are calculated respectively.The results show that the base shear and displacement of the structure considering pile-soil interaction under rare earthquake intensity are larger than that under rigid foundation assumption.The X-direction stiffness of the structure is larger than that under Y-direction stiffness.When considering pile-soil interaction,the X-and Y-direction shear and displacement increase under rare earthquake,and the Y-direction increase is more obvious,and the maximum increase is more than two times.So the design of real engineering structure Foundation flexibility should be taken into account in the calculation,otherwise the evaluation of seismic capacity of some components will lead to errors.