Structural Seismic Response Mitigation using Optimized Vibro-Impact Nonlinear Energy Sinks

Qian

Struct Control Health Monit

et al. 2019

In this paper, to enhance passive targeted energy transfer, a novel nonlinear energy sink (NES) system is developed. The NES system integrates negative stiffness obtained through geometrical nonlinearities, friction, and sliding mass. Considering a one-story shear frame, governing equations of the NES system are developed and substantiated through experimental work. The governing equations of the system were subsequently used to select the optimal design parameters. The experimental results validate the numerical predictions that a significant fraction of energy introduced directly to the primary structure by seismic excitation is transferred to the present NES and dissipated. The seismic performance of the present NES is compared with those of the linear tuned mass damper and the cubic NES. The comparison shows that the attenuation observed under the present NES control is competitive and is robust with respect to variation of the primary structural stiffness. Numerically, further sensitivity analysis was carried out to investigate the effect of peak ground acceleration values and stiffness ratio.

F = 2 k ((), u - u_{c}) ((), 1 - l {(l_{0}^{2} + {((), u - u_{c})}^{2})}^{- 1 / 2}) + f,

where k and l are the constant stiffness and relaxation length of the hinged spring, respectively, and

u_{c} = \sqrt{l^{2} - l_{0}^{2}} .

…”

Section: Problem Formulationmentioning

confidence: 99%

Section: Performance Optimizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Seismic performance of a nonlinear energy sink with negative stiffness and sliding friction

Qian

Struct Control Health Monit

et al. 2019

“…When investigating the vibration mitigation effect of the NES, the selection of performance measures is very important. In different excitation conditions, researchers adopted different or even multiple indexes, e.g., energy dissipation rate and energy decaying duration in impulsive excitation [28][29][30][31], amplitude of the main system, energy dissipation rate of the NES, energy of the entire system, and transmissibility in harmonic excitation [23,26,32,33], transition probability densities of transmissibility and input energy absorption percentage of the main system in combined harmonic and random excitation [34], and displacement, acceleration, and shear force of the main system in seismic excitation [9,35]. From these studies, the vibration mitigation effect of the NES in harmonic excitation is mainly judged by the absolute number and rate of amplitude and energy.…”

Section: Introductionmentioning

confidence: 99%

Performance evaluation and design criterion of a bistable nonlinear energy sink

Ding

Wang

2021

Preprint

In the evaluation of the vibration mitigation effect of a nonlinear energy sink (NES), the selection of performance measures is important. Based on a square root model, this paper aims to propose new reasonable performance measures and new design criteria of the NES in harmonic excitation. To broaden the application range of the slow invariant manifold, coordinate correction is carried out for the square root model of the bistable NES. Two original performance measures (the displacement amplitude of the main system and the energy dissipation rate of the NES) and two new performance measures (the mechanical energy and the input energy of the main system) are compared. The optimal geometric configuration and response form of the NES are found in different excitation conditions. The results show that the energy dissipation rate of the NES is not competent to evaluate the performance of the NES in harmonic excitation, while the two new performance measures show competence. By adjusting the geometry parameter, the nonlinear vibration absorber with positive linear stiffness and the bistable NES show optimal vibration mitigation effect in small and large excitation amplitudes, respectively. The optimal response form is the periodic response rather than the strongly modulated response.

Struct Control Health Monit

“…Furthermore, an NES system composed by several bumper NESs has been tested on a large‐scale nine‐story frame under impulsive and blast excitations . The bumper NES is another realization method of nonlinear restoring force that makes use of the nonsmooth zig‐zag function, and it is also named as Vibro‐Impact NES . In addition, tracks with specific shapes are used to realize the nonlinearity of restoring force and this type of NES is defined as Type II NES .…”

Section: Introductionmentioning

confidence: 99%

Optimization design and experimental verification of track nonlinear energy sink for vibration control under seismic excitation

Lü

Zhongpo

2017

Nonlinear energy sinks (NES) are efficient vibration control devices, which have been studied and applied in mechanical, automobile, and aerospace engineering.However, there are few applications in civil engineering. A new type of NES, which is termed as track NES, is proposed in this paper. The optimal mass ratio and track shape expression of NES were determined based on a preliminary optimization design process. To verify its vibration control effects on building structures, a series of shake table tests were conducted on a five-story steel frame. Tracks of the NES were installed at the roof of the frame with rigid connections and the mass of the NES was constrained to slide along the track by using wheels. Five earthquake waves with different frequency spectrums were selected to excite the frame coupled with NES under minor, moderate, and major levels. Accelerations and displacements on each story of the frame were measured, recorded, and evaluated. The experimental results demonstrate that with small mass ratio (2%) of main structure, NES has good performance in reducing the dynamic responses of the frame under seismic excitations. The reduction ratio for peak response is up to 50%, while for root mean square response is up to 80%. NES also exhibits wide-band frequency vibration controlling attributes, and the responses of the frame are reduced in multiple vibration modes. In addition, the vibration reduction capability of the NES with steel wheels and that with rubber wheels are compared, and it is verified that different damping of NES makes a difference to the vibration control effects. The displacement reduction performance is not sensitive to the damping factor of the NES, but acceleration response is highly affected by the damping feature of the NES.