Research On Seismic Performance Of NES Vibration Damper Based On Quasi-Zero-Stiffness Principle

At present,passive control has always been the main technical means applied to the seismic design of engineering structures because of its good shock absorption effect,no need for external energy,simple structure,and convenient construction.With the characteristics of variable stiffness and strong energy dissipation capacity,it is a passive shock absorption system that has been widely used in the field of structural passive control research in recent years.On the basis of the traditional NES shock absorber,this paper introduces a new principle—the principle of quasi-zero stiffness,and constructs a quasi-zero stiffness system through negative stiffness springs to realize a horizontal quasi-zero stiffness NES shock absorber.The shock absorber is the research object,and its anti-seismic performance is studied by using the quasi-static test method.The main research contents are as follows:1.Analysis of the damping principle of negative stiffness NES damping system.In this paper,the concept and mechanical principle of negative stiffness are analyzed briefly,and the mechanical equation of negative stiffness spring is derived.The relationship between the dynamic amplification factor and the frequency ratio of the system under different negative stiffness coefficients is derived,and it is verified that the introduction of negative stiffness has a great influence on the natural frequency of the NES system under any damping ratio of the system.The narrow-frequency damping of the common NES is extended to broadband damping,which can cover most of the low-frequency areas.Through theoretical analysis,the restoring force model of NES was obtained,the force-displacement relationship curve of the system was obtained,and the conditions satisfying the quasi-zero stiffness were determined.2.A quasi-zero stiffness NES damping system with X-type cross spring is designed.The force and displacement curves of this quasi-zero stiffness system are derived by taking the oscillator as the balance point at the central position of the shock absorber.The spring stiffness,the length-width ratio of the spring travel and the precompression of the spring were determined as the parameter variables of the quasi-zero stiffness NES damping system,and according to the actual components,a test device capable of carrying out pseudo-static loading was designed.3.Reciprocating loading test was carried out on NES shock absorber components to obtain force-displacement hysteresis curves under different working conditions.The effects of different length-width ratio and precompression of spring on the zero stiffness equilibrium position and the seismic performance of the system are analyzed.The material compression test was carried out on spring members of different lengths under different working conditions,and the vibration table was used to conduct modal test on the zero-stiffness NES shock absorber,and the frequency range and excellent frequency of the shock absorber were obtained.The ABAQUS finite element software was used to simulate the zero-stiffness NES shock absorber,and the influence of two variables on the seismic performance of the shock absorber was analyzed under the condition that the guide rod had no friction and the spring did not have lateral buckling.The research results show that: 1.According to the system force-displacement relationship deduced from the dynamic equation,the rationality of realizing the quasi-zero stiffness system through the pre-compressed spring is theoretically verified.Furthermore,constructing a quasizero stiffness system in the traditional NES shock absorber can improve the damping performance of the shock absorber to a certain extent.2.Under the same aspect ratio,increase the pre-compression of the spring to align with the zero stiffness system.The balance position is affected,and the energy consumption near the balance point also increases to a certain extent;in the case of a fixed spring precompression,the maximum bearing capacity of the system decreases with the increase of the aspect ratio.3.The modal test analysis shows that the quasizero stiffness NES shock absorption system under various working conditions has broadband shock absorption characteristics,and the excellent frequency range is 1.89Hz～12.49 Hz,basically covering the natural frequencies of most low-frequency building structures,and can After the frequency changes under the influence of earthquake damage,etc.,the structure still has an effective control effect on the structural vibration.