Vibration Reduction Model Test And Numerical Simulation Of Building Structure Over Metro

In recent years,with the rise and development of subway-covered properties,major cities in my country,including Beijing,Shanghai,Shenzhen,and Hangzhou,have tried and developed subway-covered properties.However,because the foundation of the property above the subway is directly placed above the vibration source,its vibration sensitivity is stronger than the buildings along the subway.Although the vibration caused by subway trains is generally lower than the structural damage level,it will not cause direct damage like earthquakes,but it can cause local vibration of structures and indoor facilities,generate secondary structural noise,and make people feel uncomfortable.In order to study the propagation rule and influencing factors of vibration in the superstructure,this paper designed a set of structural vibration test models,and carried out loading and test analysis in the laboratory to discuss reasonable design parameters and vibration reduction methods.On this basis,an analysis of the vibration response and damping effect of the property subway-covered properties was conducted.The main research work and conclusions completed in this article are as follows:(1)First,the theories related to subway operation are introduced,including the mechanism and source of train vibration,the characteristics of vibration,and the wave equation and attenuation law of elastic waves.The impedance concept of the building structure and the impedance expression of each part are introduced,and the first frequencies of the simply supported and fixed-sided plates deduced based on the energy method are given,which provides a theoretical basis for model tests and vibration reduction analysis.(2)The vibration response test of the subway superstructure property model was carried out,and the structural vibration response of 6 sets of vibration frequencies and 54 structural parameters was obtained.It were found that when the external excitation was 30 Hz,the structural vibration response was the largest.When the plate thickness is increased and the cross-sectional area of the column is increased,the vibration of the structure is reduced,and the vibration reduction effect of increasing the plate thickness is more obvious.Therefore,the vibration response can be reduced by properly selecting the geometric parameters of the structure and controlling the natural frequency of the structure.Based on the vibration response test,the vibration damping test was carried out.After adding the vibration damping pad,the acceleration peaks of the measurement points of each layer under different frequency excitations were reduced.Among them,the vibration response under 30 Hz excitation had the most significant reduction,and the overall vibration damping effect was good..(3)The finite element modeling of the model test was carried out.Based on this,the simulation of the model test was carried out and compared with the test data.The two generally agreed well.Finally,the reasons for the difference between the test and the simulation are analyzed,including the warpage of the test board itself,the voids generated when the test board and the frame overlap.On this basis,a six-story,eight-story structure simulation was conducted to further analyze the law of vibration response changing with floors.(4)The principle of overall vibration reduction of the structure and the simulation of vertical vibration reduction bearings in SAP2000 are introduced,and an eight-layer frame structure is established.Using the measured train vibration acceleration as input excitation,the acceleration response law under subway vibration was analyzed,and the influence of structural parameter changes on vibration response was discussed.On this basis,local and overall vibration reduction measures were verified.