Study On Vibration Analysis Model Of Over-track Buildings On Metro Depots Based On Method Of Loss Factor Fitting

In recent years,over-track buildings on metro depots have developed rapidly,but metro train-induced vibrations affect the work and life of residents in the over-track buildings.Due to the special architectural form of the over-track building,the vibration problem is different from that of buildings near the regular metro line,which needs special research.The numerical simulation method is usually used to predict and analyze the vibration response in the design stage.The selection of damping model has great influence on the calculation results in modeling.In this paper,the damping model and value of over-track buildings were analyzed,and a loss factor fitting method based on measured data was proposed.The main work and conclusions are as follows:(1)The necessity of applying frequency-dependent damping model in the vibration analysis model of over-track buildings was analyzed based on the environmental vibration of over-track buildings on metro depots induced by trains.(2)The over-track building was simplified into column(beam)structure and plate(wall)structure.For the two types of components,a method of frequency-dependent loss factor fitting based on measured data was proposed.The limitation of this method was analyzed by an example.There is a critical frequency in the frequency-dependent loss factor fitting.The conclusion is that the critical frequency of the structures is mainly related to the size.(3)The frequency-domain finite element method was compiled by MATLAB software with the loss factor fitting method being applied.The frequency-domain finite element analysis model of the over-track building on metro depots was obtained.(4)The hammer vibration test and numerical simulation analysis of column(beam)structure were carried out in an underground garage of Beijing Jiaotong University.Based on the test data,the frequency-dependent loss factor curve of column(beam)structure was obtained,and its correctness was verified by using the modal analysis results.(5)The hammering vibration measurement and numerical simulation analysis of the plate(wall)structure were carried out in over-track buildings of a metro depot.Based on the measurement data,the frequency-dependent loss factor curve of the plate(wall)structure was obtained by using the MATLAB frequency-domain finite element program,and its correctness was verified by the modal analysis results.(6)Taking the over-track buildings of a metro depot as the background,a twodimensional finite element model was established by MATLAB program.The frequencydependent loss factors of column(beam)and plate(wall)structures obtained in this paper were input to solve the vibration response and attenuation law of the platform and overtrack buildings of metro depot induced by trains.By comparing the measured and calculated values of the vibration attenuation law,it is found that the vibration responses of the two are close,and the vibration responses are basically consistent with the attenuation law of the floor.Therefore,the feasibility of the vibration prediction method for over-track buildings of metro depots based on the measured fitting frequencydependent loss factor is verified.