Experimental study of track nonlinear energy sinks for dynamic response reduction

Earthq Engng Struct Dyn

Wierschem

Spencer

et al. 2015

Self Cite

Summary This paper proposes a single‐sided vibro‐impact track nonlinear energy sink (SSVI track NES) as an effective way to mitigate the effects of impulsive and seismic excitation on building structures. The SSVI track NES is a passive energy dissipation device, which consists of a mass moving along a track, the shape of which provides a nonlinear restoring force to the mass. Previous studies have analyzed the track NES, which considers the track shape to be smooth and symmetric. By introducing a discontinuity into the shape of the track (e.g., through impact), energy in the primary structure can be scattered to higher frequency responses where it can be dissipated at a faster rate. First, the SSVI track NES is analytically investigated and numerically optimized base on a two degree‐of‐freedom primary structure. The results of numerical simulations show that the SSVI track NES can be more efficient than both the track NES and tuned mass damper in reducing the response of the primary structure. Based on the analytical studies, the SSVI track NES is experimentally realized and investigated when subjected to both impulse‐like and seismic excitations, confirming the numerical predictions and validating the analytical model of the device. Finally, the robustness of the SSVI track NES is investigated numerically. The results of this investigation indicate that the SSVI track NES remains effective over a broad range of input excitation energy levels, as well as during significant changes in the stiffness of the primary structure. Copyright © 2015 John Wiley & Sons, Ltd.

Section: Introductionmentioning

confidence: 99%

Numerical and experimental study of the performance of a single‐sided vibro‐impact track nonlinear energy sink

Earthq Engng Struct Dyn

Wierschem

Spencer

et al. 2015

Self Cite

“…[43][44][45] Both experimental and numerical studies have been carried out to demonstrate the robustness of NESs against changes in the natural frequency of primary structures. [46][47][48][49][50][51][52][53] NESs have been realized on test structures with different scales by means of arranging geometric springs, 46 shaping elastic bumpers, 49,50 and utilizing curved movement path. [51][52][53] Figure 1 shows the configuration of the cubic NESs, in which the nonlinearity is obtained by the geometric arrangement of elastic springs.…”

Section: Introductionmentioning

confidence: 99%

“…[46][47][48][49][50][51][52][53] NESs have been realized on test structures with different scales by means of arranging geometric springs, 46 shaping elastic bumpers, 49,50 and utilizing curved movement path. [51][52][53] Figure 1 shows the configuration of the cubic NESs, in which the nonlinearity is obtained by the geometric arrangement of elastic springs. The auxiliary mass is connected to the fixtures on the primary structure by a pair of elastic springs placed perpendicularly to the moving direction.…”

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

Self Cite

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.

“…Traditional passive TMDs have the widest application in real projects; however, they have the disadvantage of high sensitivity to frequency deviation with the primary structural frequency, and they also have difficulty adjusting the frequency . To solve this problem, several adaptive and semiactive TMDs have been proposed, for example, the semiactive independent variable stiffness device, a semiactive TMD with variable stiffness and damping, and an adaptive length SMA pendulum smart TMD .…”

Section: Introductionmentioning

confidence: 99%

An adaptive‐passive retuning device for a pendulum tuned mass damper considering mass uncertainty and optimum frequency

Struct Control Health Monit

Shi

et al. 2019

127

A tuned mass damper (TMD) is one of the most used structural control devices. However, a traditional TMD has the disadvantage of high sensitivity to frequency deviation and difficulty adjusting the frequency. The optimal frequency for a TMD is dependent on the structural dominant frequency and the TMD mass ratio. Nevertheless, the actual structural modal mass is difficult to obtain, and the presence of a TMD may interfere with identification of the natural structural frequency. Aiming to control wind-induced vibration, an adaptive-passive retuning device is developed for a pendulum TMD called an adaptive-passive variable pendulum TMD (APVP-TMD). When it is time to adjust the pendulum, the mass will first be locked, and the structural frequency in this case is identified through wavelet transformation by an acceleration sensor and a microcontroller. It is found that this is actually the optimal frequency for the TMD. Then, a stepper motor will adjust the length of the pendulum under the guidance of the microcontroller. The effectiveness of APVP-TMD is verified through both discrete and continuous models. For the discrete model, a single-degree-offreedom primary structure coupled with an APVP-TMD is presented as an experiment with analysis comparison, and a five-degree-of-freedom primary structure coupled with an APVP-TMD is proposed as a numerical simulation. For the continuous model, a wind-sensitive concrete chimney is controlled by an APVP-TMD as a case study. The results all show that the APVP-TMD can identify the optimal frequency and retune itself effectively, and the retuned TMD has better vibration control than the mistuned one.