Study On Vibration Control Technology Of Linear And Nonlinear Joint Structure Control

Tuned mass dampers(TMDs)are a type of structural control method which is realized by tuning to the primary structure frequency-wise.An in-tune TMD can effectively dissipate energy and mitigate structural responses through its large resonat vibration.However,TMDs are less effective when they are detuned.Nonlinear energy sinks(NESs),on the contrary,are robust against such frequency change with their nonlinear force-displacement relationship but dependent on the input energy level for optimal control capacity.In this thesis,five types of structural control methods including single mass dampers(SMDs),dual mass dampers(DMDs),asymmetric nonlinear energy sinks(Asym NESs),vibro-impact dual mass dampers(VI DMDs),and single-sided vibro-impact asymmetric nonlinear energy sinks(SSVI Asym NESs)are proposed.These devices combine the advantages of frequency robustness of NES and energy robustness of TMD.Based on the equations of motion of the proposed linear-nonlinear joint control devices,numerical analysis and experimental study are carried out.1.The analytical study of SMDs and DMDs is carried out.Firstly,the numerical models of a two-degree-of-freedom main structure using different control methods are established,and the mass ratio and stiffness of the SMD and the DMD are optimized under impulsive loadings.The results show that the nonlinear-linear joint control methods have an good vibration reduction performance similar to and high robustness better than the NES and the TMD.Furthermore,the DMD is found better than the SMD.Then,the VI DMD is proposed on the basis of the DMD,pass through collision between the two small masses increases the energy consumption.Then the numerical model of a realistic three-story small-scale steel structure is used to study the control perofromance of the SMD and the DMD,providing a foundation for the experimental study thereafter.2.The Asym NES is analytically studied on the same three-story small-scale steel structure.The control parameters of the Asym NES are optimized under impulse loadings.Meanwhile,SSVI Asym NES which are based on the DMD and the Asym with an impact surface added to one side are realized.The results show that the Asym NES and SSVI Asym NES with the advantages of linearity and nonlinearity has high frequency-and energy-robustness.Two types of Asym NES obtained by the optimization under impulse loadings also has a good control performance under seismic loadings.3.Experimental design and validation of the control devices that have showed excellent control capacity in the numerical simulation are conducted.In the experiment,a DMD and an Asym NES,as well as an SSVI DMD and an SSVI Asym NES which are based on the DMD and the Asym with an impact surface added to one side are realized.A TMD and a type I NES(convential NES)are also considered in the experiment.The results show that for the structure with six columns per story(representing the intact structure),the DMD,Asym NES,SSVI DMD,and SSVI Asym NES are very effective in response reduction,similar to the in-tune TMD.For the structure with four columns per story(representing the damaged structure),the four newly proposed devices maintain their effectiveness due to the nonlinear restoring force.4.The experimentally validated control devices are applied to a real-scale building numerically.A realistic eight-story steel building is used as the main structure,the structural displacements of which are investigated under various loadings.The results show that the DMD,Asym NES,SSVI DMD,and SSVI Asym NES have remarkable vibration reduction capacity under impulsive and seismic loadings,demonstrating great potential in real engineering applications.