Vertical Dynamic Stiffness And Vibration Isolation Performance Of Laminated Rubber Bearing

With the shortage of urban building land and the rapid development of subway rail transit,the vibration comfort problem of subway structures and surrounding buildings caused by subway operation has become increasingly prominent,which has a significant impact on people’s quality of life and even health.As a vibration isolation device,the laminated rubber bearing is widely used in the structure on metro,and the vertical dynamic performance of the laminated rubber bearing has a good engineering application value.Based on the limitations of the existing dynamic stiffness test method,we proposed a simple test method for vertical dynamic stiffness of full-scale laminated rubber bearings under a large vertical pressure,and the vertical constant pressure is simulated by the compression shear testing machine,and the dynamic excitation is simulated by the force hammer excitation.The linear natural rubber bearing(LNR600 and LNR800)and lead rubber bearings(LRB600 and LRB800)are test objects,we carried out the vertical dynamic stiffness tests to study the vertical dynamic stiffness and vibration isolation performance of the full-scale laminated rubber bearing under different large vertical pressures.The results show that the test method of vertical dynamic stiffness is simple and effective.With the increase of the vertical pressure,the vertical dynamic stiffness peak of the laminated rubber bearing shows a trend of moving to high frequency as a whole,and the effective vibration isolation bandwidth is moving to high frequency.Based on the time-domain analysis,the vibration isolation rate of laminated rubber bearings is 60%～80%,and the vibration level attenuation is 6～13dB.Based on the frequency-domain analysis,there is a large attenuation in the vibration stage of 63～400Hz,and the maximum attenuation frequency range is located at 100～125Hz,and the maximum attenuation is 23dB.Taking the single-degree-of-freedom vibration isolation model as the research object,the simulation method of the vertical dynamic stiffness of the laminated rubber bearing in SAP2000 is determined,and the results show that the vertical connection attribute of the laminated rubber bearing is simulated based on the frequency-dependent connection attribute of SAP2000.The real and imaginary part are used as the stiffness and damping respectively,it can truly reflect the vertical output dynamic stiffness characteristics of the laminated rubber bearing.Taking the single-layer and single-span structure as the research object,comparing the influence of different analysis methods on the dynamic response of the vibration isolation structure,the results show that the vibration calculation and comfort evaluation of the structure on metro should be based on the frequency domain method of linear time history analysis(TH-NSSC-OPDS analysis method)and steady-state dynamic analysis method(FDNSSC-OPDS analysis method)based on the output dynamic stiffness.Taking the super high-rise structure on metro in Guangzhou as the research object,based on numerical analysis of SAP2000 and shaking table test,we studied the vibration propagation law and the vertical vibration isolation effect of the vibration isolation structure.The results show that the vibration isolation structure using the laminated rubber bearing changes the structural system.The structure tends to move vertically as a whole,which is conducive to the regularization of vertical mode of the structure and increases the vertical dynamic response of the structure.Based on the filtering effect of the laminated rubber bearing,the vibration isolation structure has a good vertical vibration isolation effect,with an average vibration isolation rate φ of 8.13%and an average vibration level attenuation μ of 1.92dB.