Theoretical And Experimental Study On Seismic Control Performance Of Nonlinear Energy Sink With Negative Stiffness

The nonlinear energy sink(NES)is a passive control technology of additional substructure,which is different from the traditional tuned mass damper(TMD)technology.Its control principle is by setting an additional substructure with strong nonlinear stiffness characteristics,and using the intrinsic resonant characteristics of the nonlinear system to make the dynamic response of substructure to main structure through the internal resonance capture,so a large amount energy of main structure is absorbed by substructure and dissipated.NES has a much more attractive bandwidth for vibration absorption and stronger robustness than TMD Since its control principle is no longer limited to tuning.To study new NESs with strong nonlinear restoring forces and better control over structural seismic response.The nonlinear energy sink(NES)with negative stiffness is presented for efficient and passive structural seismic response control in this article.Through the combination of numerical simulation and shaking table test,the specific innovations and work include:(1)Study the numerical algorithm of the nonlinear energy sink-seismic control system,and provide algorithm support for NES numerical simulation.Based on the numerical wavelet transform,the algorithm for constructing the response energy power spectrum is studied,which provides a simple and effective analysis method for analyzing the mechanism of NES forming a targeted energy transfer over a wide frequency domain.(2)The typical analysis model is studied by adopting NES with negative stiffness,NES with cubic nonlinear stiffness and traditional tuned mass damper(TMD),respectively.The parameters of different devices are optimized numerically,and then the comparison study on the control performances is studied.The results show that the seismic control performance of the NES with negative stiffness is superior to that with cubic stiffness.In respect to dynamic characteristic variation of the primary structure,the control performance by NES with negative stiffness shows stronger robustness than that by TMD.While in respect to variation of peak ground acceleration,the NES with negative stiffness shows robustness performance closed to TMD.(3)To explore the mechanism of seismic response control,numerial wavelet transform is applied to analyze the structural seismic response history.The analysis indicates that more intense and durable transient internal resonance captures can be obtained on wide frequency domain by NES with negative stiffness,and thus its seismic control shows higher efficiency.Furthermore,as the transient internal resonance captures are generated on multiply active frequency domain,particularly as those transient subharmonic resonance captures are insensitive to variation of fundamental frequency of the primary structure,the seismic response control performance by NES with negative stiffness possesses strong robustness.(4)Study the influence of frictional damping on the damping performance of NES with negative stiffness,including the mass ratio of the system,the peak value of the ground motion record,and the influence of the friction coefficient.The results show that the seismic control performance of NES with friction and negative stiffness basically remains the same as the NES with viscous and negative stiffness.The reasonable selection of the mass ratio of the system,the peak value of the ground motion and the friction coefficient can make the NES with friction and negative stiffness have better damping control performance.(5)Study the influence of the additional vibro-impact device on the seismic control performance of NES with negative stiffness,including the influence of the negative-stiffness NES control system on the seismic response and the robustness of seismic control,and analyze the NES with negative stiffness of the different vibration-impact device materials Impact of shock absorption performance.The results show that under the optimal parameter control,the additional vibro-impact device can improve the damping control performance of NES with negative stiffness.(6)Design and manufacture NES device model with negative stiffness.Shaking table experiments were performed on single-and four-layer steel frame models with negative stiffness NES.Based on the experimental data,the seismic control performance of NES with negative stiffness and its influencing factors are analyzed.Finally,the rationality of the theoretical analysis is verified by comparing the experimental results with the numerical simulation.