4 research outputs found
Numerical studies of the conventional impact damper with discrete frequency optimization and uncertainty considerations
AbstractThis paper presents the performance of a single horizontal conventional Impact Damper (ID) in both wide range frequency and resonance excitations. The effects of the coefficient of restitution, e, mass ratio, μ, and clearance, d, on the performance of ID are investigated. The optimal parameters are numerically found by discretely varying the clearance and excitation frequency. The performance of optimal ID is discussed, with respect to different parameters, in both resonance and off-resonance modes. In addition, it is shown how the efficiency of the optimal conventional ID is deteriorated as a result of mistuning in the amplitude and frequency of excitation. This is estimated by suggesting a new criterion of post processing data. It is shown that an ID designed to resist high amplitude excitation is able to perform well at lower amplitude. However, the opposite trend can significantly deteriorate the efficiency of optimal ID. In regard to excitation frequency, the ID, optimized with respect to a wide range of frequency, is less sensitive to frequency mistuning. Finally, the vulnerability of the optimized ID versus uncertainties in structural parameters is clearly determined and it is illustrated that less robustness occurs when the performance of the controller is more efficient
EVALUATING BEHAVIOR OF HIGH-RISE STRUCTURES EQUIPPED WITH IMPACT DAMPER UNDER NEAR- AND FAR-FIELD EARTHQUAKES
Impact damper is considered as a passive control system. Experimental and analytical studies have shown that this group of non-linear dampers has a better performance than linear vibratory neutralizers in terms of reducing structural vibrations. The main factor influencing this type of damper in controlling vibrations is that the small forces, created by moving masses of impact dampers reduce sharp vibrations by creating disruption in the oscillation range of the structure.So far, modeling of the impact damper has been conducted solely through MATLAB software. Naturally, the functional aspects of this software are limited in research and development aspects compared to the common programs such as SAP2000 and ETABS. In this study, using SAP2000 software in modeling impact dampers, relatively tall building models are used to compare the performances
of impact damper in high-rise buildings, and the seismic performance of such buildings with impact damper is investigated. The purpose of this study is to evaluate the performance of impact damper in tall buildings and to determine the best placement of damper in reducing the amplitude response of the system under vibration.In order to achieve favorable results for tall buildings under seismic vibration, both near- and far-field earthquakes are selected and applied to 10- and 25-story steel buildings. The analysis used in this study is of nonlinear time-history kind, and the design of structural elements is performed considering AISC360-10 Code requirements. One of the main results of this study is the decreased amplitude response of 10 and 25-story steel buildings under vibration due to the placement of impact damper on the roof up to 14\% and 16\% under far- and near-field earthquakes, respectively. It is also observed that if the height and number of openings increase, the effect of the placement of impact damper in the middle floors will become closer to the placement of damper on the roof due to the combination of vibration modes