Discussion of system intrinsic parameters of tuned mass dampers used for seismic response reduction

Earthq Engng Struct Dyn

Zhang

et al. 2021

Nonlinear energy sinks (NESs) have outperformed tuned mass dampers in mitigating undesired responses against changes in structural frequencies. However, the dilemma of gaining frequency robustness at the cost of energy sensitivity as well as the large masses of devices required for civil engineering structures impede the applications of existing NESs. To solve the issue of lacking energy robustness and take advantage of inerters to reduce physical mass, an asymmetric NES‐inerter (Asym NESI) is developed in this study. This passive inerter‐based nonlinear mass damper is configured based on an energy‐robust NES with an inerter added between the auxiliary mass and a fixed point. The paper commences with the formulation of the Asym NESI through mathematical derivations. Then an Asym NESI is designed and evaluated on a three‐story structure in comparison with other counterpart mass dampers. The effectiveness of the Asym NESI can be attributed to its unique dynamics which are revealed analytically using the harmonic balance method through free vibrations and harmonically forced vibrations. The ensuing numerical validations show that due to the integrated linear and nonlinear dynamics of the Asym NESI, the proposed device exhibits strong robustness against changes in both structural frequency and energy level. Moreover, driven by the large inertial effect induced by the auxiliary inerter, the Asym NESI shows flexibility in choosing a practical installation location without sacrificing excellent control capacity. Importantly, the benefits of the Asym NESI are further confirmed by the responses subjected to a suite of ground motions. This study provides analytical insights into the effectiveness and robustness of Asym NESIs and demonstrates substantial performance enhancement by the inerter in structural response mitigation.

Section: Introductionmentioning

confidence: 99%

Effectiveness and robustness of an asymmetric nonlinear energy sink‐inerter for dynamic response mitigation

Earthq Engng Struct Dyn

Zhang

et al. 2021

“…Meanwhile, researchers also extended it into the community of earthquake engineering in the past years. Some optimum TMD parameters and optimization algorithms have been derived under various types of ground excitations, part of which considered the uncertainties resulted from the changing environment . However, the seismic response mitigation of conventional TMDs had not been effective because the TMD had little effect on the maximum responses under earthquakes .…”

Section: Introductionmentioning

confidence: 99%

“…Some optimum TMD parameters and optimization algorithms have been derived under various types of ground excitations, [10][11][12] part of which considered the uncertainties resulted from the changing environment. [13][14][15][16][17][18] However, the seismic response mitigation of conventional TMDs had not been effective because the TMD had little effect on the maximum responses under earthquakes. 19 Additionally, a considerable mass of TMD was required to achieve a sizeable reduction in the response, especially for structures with large damping ratios, 6 which in turn compromised the applicability of TMDs.…”

Section: Introductionmentioning

confidence: 99%

Experimental and numerical studies of a novel asymmetric nonlinear mass damper for seismic response mitigation

Struct Control Health Monit

Liu

et al. 2020

Summary This paper proposes a novel passive mass damper, namely, asymmetric nonlinear energy sink (Asym NES), which is characterized by integrating linear and nonlinear restoring forces to mitigate the unwanted responses of building structures. The Asym NES, configured based on a cubic NES, consists of an auxiliary mass connected to the primary structure through a linear and nonlinear springs. These two springs are statically balanced at a deformed position, producing an asymmetric restoring force in the Asym NES. The study commences with a detailed working principle of the Asym NES, and the equations of motion of an Asym NES‐attached system are derived. Subsequently, experimental studies on the Asym NES designed for a small‐scale three‐story steel frame are conducted; the natural frequencies of which can be altered by changing the number of columns per story. Moreover, the performance of the Asym NES is compared with a tuned mass damper (TMD) and a cubic NES under impulsive excitations. Test results demonstrate the effectiveness of the Asym NES as well as its robustness against changes in the structural frequency. Following the experimental studies, the validated Asym NES model is further applied in the numerical investigation on a six‐story benchmark building to highlight its effectiveness and robustness in potential practical applications. Besides the impulsive excitations, an ensemble of 106 seismic ground motions with wide‐ranged energies is applied to the structures with original and decreased frequencies. Numerical results show that the proposed Asym NES is as effective as the in‐tune TMD in response mitigation under seismic excitations and exhibits strong robustness against changes in both the energy level and the structural frequency. The ingenious design and excellent efficiency of the Asym NES can offer a promising type of high‐performance device for structural control under extreme events.

“…Passive control technology has been gaining wide acceptance. There are lots of successful paradigms, among which seismic isolation, viscous dampers, viscoelastic dampers, metallic dampers, friction dampers, tuned liquid dampers, and tuned mass dampers, are widely applied. However, seismic isolation techniques, such as laminated rubber bearing, may lose efficacy under near‐fault earthquakes owing to the excessive horizontal displacement of the isolation bearing.…”

Section: Introductionmentioning

confidence: 99%

Particle impact dampers: Past, present, and future

Struct Control Health Monit

Masri

Lü

2017

201

105

Particle damping, an effective passive vibration control technology, is developing dramatically at the present stage, especially in the aerospace and machinery fields. The aim of this paper is to provide an overview of particle damping technology, beginning with its basic concept, developmental history, and research status all over the world. Furthermore, various interpretations of the underlying damping mechanism are introduced and discussed in detail. The theoretical analysis and numerical simulation, together with their pros and cons are systematically expounded, in which a discrete element method of simulating a multi-degree-of-freedom structure with a particle damper system is illustrated. Moreover, on the basis of previous studies, a simplified method to analyze the complicated nonlinear particle damping is proposed, in which all particles are modeled as a single mass, thereby simplifying its use by practicing engineers. In order to broaden the applicability of particle dampers, it is necessary to implement the coupled algorithm of finite element method and discrete element method. In addition, the characteristics of experimental studies on particle damping are also summarized. Finally, the application of particle damping technology in the aerospace field, machinery field, lifeline engineering, and civil engineering is reviewed at length. As a new trend in structural vibration control, the application of particle damping in civil engineering is just at the beginning. The advantages and potential applications are demonstrated, whereas the difficulties and deficiencies in the present studies are also discussed. The paper concludes by suggesting future developments involving semi-active approaches that can enhance the effectiveness of particle dampers when used in conjunction with structures subjected to nonstationary excitation, such as earthquakes and similar nonstationary random excitations. KEYWORDS discrete element method, impact damping, nonlinear energy sink, particle damping, passive control, semiactive control | INTRODUCTIONParticle damping technology is a form of an auxiliary-mass type vibration damper, wherein multiple metal, tungsten carbide, ceramic or other types of small particles are placed within the cavities of the vibrating structure, or the enclosures attached to the vibrating structure in order to mitigate the response of the primary structure. [1,2] As the primary structure vibrates, kinetic energy is significantly absorbed through the combined effects of particle-to-particle and particle-to-wall inelastic collisions and frictional losses, producing considerable damping to the primary structure. [3][4][5][6] Particle damping technology has been widely Received: 23 February 2017 Revised: used due to its conceptual simplicity, moderate cost, good durability, and temperature insensitivity. Provided that the operating temperature is below the particles' metal melting point, it could maintain normal operation. Furthermore, material such as tungsten powder can withstand the high temp...