• 한국지진공학회논문집
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• 제11권2호
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• pp.47-56
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• 2007

본 연구에서는 지진하중을 받는 탄성 및 비탄성 구조물에 대하여 수동 및 준능동 TMD의 지진응답제어성능을 평가하였다. 먼저 기존의 연구에서 제안된 식을 사용하여 최적 설계된 수동형 TMD와 본 연구에서 제시된 준능동 TMB가 설치된 탄성 구조물의 변위스펙트럼을 구하였으며, 준능동 TMD가 TMD보다 작은 스트로크를 가지고도 최대변위응답제어에 있어 우수함을 확인하였다. 또한 구조물의 주기와 TMD의 주기가 일치하지 않은 경우의 성능저하에 대한 TMD의 강인성을 평가하였다. 최종적으로 Bouc-Wen 모델을 사용하여 모사된 비탄성이력 특성을 가지는 구조물에 대한 수치해석을 수행하였으며, 이를 통해 탄성구조물에 대하여 최적화된 수동형 TMD의 성능은 구조물 응답의 비탄성이력 부분이 증가함에 따라 크게 저하되는 반면 준능동 TMD는 수동형 TMD보다 약 15-40% 정도의 더 많은 응답감소효과를 가짐을 확인하였다.

• Smart Structures and Systems
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• 제8권3호
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• pp.239-252
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• 2011

In this study, the performances of a passive tuned mass damper (TMD) and a semi-active TMD (STMD) were evaluated in terms of seismic response control of elastic and inelastic structures under seismic loads. First, elastic displacement spectra were obtained for damped structures with a passive TMD and with a STMD proposed in this study. The displacement spectra confirmed that the STMD provided much better control performance than passive TMD and the STMD had less stroke requirement. Also, the robustness of the TMD was evaluated by off-tuning the frequency of the TMD to that of the structure. Finally, numerical analyses were conducted for an inelastic structure of hysteresis described by the Bouc-Wen model. The results indicated that the performance of the passive TMD whose design parameters were optimized for an elastic structure considerably deteriorated when the hysteretic portion of the structural responses increased, and that the STMD showed about 15-40% more response reduction than the TMD.

• 한국지진공학회논문집
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• 제11권2호
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• pp.57-68
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• 2007

메가골조시스템은 사용되는 구조재료를 절약하면서도 구조물의 강성을 효과적으로 높일 수 있는 장점 때문에 고층건물의 설계에 많이 사용되고 있다. 이러한 메가골조시스템이 주로 적용되고 있는 초고층건물의 구조설계에서는 횡하중에 대한 거주자의 불안감을 최소화시키는 것이 주요한 관심사중의 하나이다. 따라서 본 연구에서는 메가골조구조물의 사용성을 향상시키기 위한 방법으로 일반적인 수동 TMD의 제어성능을 개선한 준능동 TMD(STMD)를 사용하였다. 이를 위하여 TMD에서 일반적으로 사용되고 있는 수동감쇠기 대신 준능동 MR 감쇠기를 사용하여 STMD를 구성하였다. 메가골조구조물의 일반적인 유한요소해석모델은 매우 많은 수의 자유도로 구성되어 있기 때문에 원형모델을 사용하여 STMD의 제어성능을 검토하는 것은 현실적으로 불가능하다. 따라서 메가골조구조물의 동적 거동을 정확하게 표현할 수 있는 최소한의 자유도를 가진 응축모델을 행렬응축기법을 이용하여 제안하였다. 또한 일반적인 행렬응축기법의 효율성을 향상시키기 위하여 메가골조구조물의 특성을 활용한 다단계 행렬응축기법을 제안하였다. 본 연구에서 제안된 응축모델을 사용한 제어의 효율성과 정확성 및 메가골조구조물에 대한 STMD의 제어성능을 예제해석을 통하여 검증하였다.

• Smart Structures and Systems
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• 제20권5호
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• pp.525-537
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• 2017

This paper explores different vibration control strategies for the cancellation of human-induced vibration on a structure with time-varying modal parameters. The main motivation of this study is a lively urban stress-ribbon footbridge (Pedro $G\acute{o}mez$ Bosque, Valladolid, Spain) that, after a whole-year monitoring, several natural frequencies within the band of interest (normal paring frequency range) have been tracked. The most perceptible vibration mode of the structure at approximately 1.8 Hz changes up to 20%. In order to find a solution for this real case, this paper takes the annual modal parameter estimates (approx. 14000 estimations) of this mode and designs three control strategies: a) a tuned mass damper (TMD) tuned to the most-repeated modal properties of the aforementioned mode, b) two semi-active TMD strategies, one with an on-off control law for the TMD damping, and other with frequency and damping tuned by updating the damper force. All strategies have been carefully compared considering two structure models: a) only the aforementioned mode and b) all the other tracked modes. The results have been compared considering human-induced vibrations and have helped the authors on making a decision of the most advisable strategy to be practically implemented.

• Smart Structures and Systems
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• 제23권2호
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• pp.155-171
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• 2019

In this study, Semi-active Tuned Mass Dampers (STMDs) are employed in order to cover the prevailing uncertainties and promote the efficiency of the Tuned Mass Dampers (TMDs) to mitigate undesirable structural vibrations. The damping ratio is determined using type-1 and type-2 Fuzzy Logic Controllers (T1 and T2 FLC) based on the response of the structure. In order to increase the efficiency of the FLC, the output membership functions are optimized using genetic algorithm. The results show that the proposed FLC can reduce the sensitivity of STMD to excitation records. The obtained results indicate the best operation for T1 FLC among the other control systems when the uncertainties are neglected. According to the irrefutable uncertainties, three supplies for these uncertainties such as time delay, sensors measurement noises and the differences between real and software model, are investigated. Considering these uncertainties, the efficiencies of T1 FLC, ground-hook velocity-based, displacement-based and TMD reduce significantly. The reduction rates for these algorithms are 12.66%, 26.43%, 20.98% and 21.77%, respectively. However, due to nonlinear behavior and considering a range of uncertainties in membership functions, T2 FLC with 7.2% reduction has robust performance against uncertainties compared to other controlling systems. Therefore, it can be used in actual applications more confidently.

• Smart Structures and Systems
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• 제30권1호
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• pp.89-106
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• 2022

The negative stiffness of an active or semi-active damper system has been proven to be very effective in reducing dynamic response. Therefore, energy dissipation devices possessing negative stiffness, such as viscous inertial mass dampers (VIMDs), have drawn much attention recently. The control performance of the VIMD for cable vibration mitigation has already been demonstrated by many researchers. In this paper, a new optimal design procedure for VIMD parameters for taut cable vibration control is presented based on the fixed-points method originally developed for tuned mass damper design. A model consisting of a taut cable and a VIMD installed near a cable end is studied. The frequency response function (FRF) of the cable under a sinusoidal load distributed proportionally to the mode shape is derived. Then, the fixed-points method is applied to the FRF curves. The performance of a VIMD with the optimal parameters is subsequently evaluated through simulations. A taut cable model with a tuned VIMD is established for several cases of external excitation. The performance of VIMDs using the proposed optimal parameters is compared with that in the literature. The results show that cable vibration can be significantly reduced using the proposed optimal VIMD with a relatively small amount of damping. Multiple VIMDs are applied effectively to reduce the cable vibration with multi-modal components.

• 한국공간구조학회논문집
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• 제7권2호
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• pp.53-61
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• 2007

경간이 길어지고 강성이 유연한 바닥판 구조물은 처짐과 진동에 같은 사용성에 있어서 많은 문제점을 가지고 있다. 따라서 다양한 진동제어 시스템이 제공되고 있으며 TMD와 같은 수동제어 시스템은 적용에 있어서 한계가 있다. 본 논문에서는 MR감쇠기와 TMD를 조합한 준능동 TMD의 제어기법에 따른 제어성능을 알아보았다. 준능동 TMD의 감쇠기를 Groundhook 모델로 모형화한 경우에 주구조물인 바닥판 구조물의 진동제어에 있어서 보다 효과적인 것을 볼 수 있으나 TMD의 변위를 제어해야 하는 경우에 준능동 TMD의 감쇠기를 Skyhook 모델로 모형화하여 진동을 제어할 필요가 있다. 그리고 바닥판 구조물과 TMD를 동시에 제어해야하는 경우에는 Hybrid 제어기법이 우수한 제어성능을 보이고 있다.

• 한국공간구조학회논문집
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• 제21권1호
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• pp.79-86
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• 2021

Control performance of a smart tuned mass damper (TMD) mainly depends on control algorithms. A lot of control strategies have been proposed for semi-active control devices. Recently, machine learning begins to be applied to development of vibration control algorithm. In this study, a reinforcement learning among machine learning techniques was employed to develop a semi-active control algorithm for a smart TMD. The smart TMD was composed of magnetorheological damper in this study. For this purpose, an 11-story building structure with a smart TMD was selected to construct a reinforcement learning environment. A time history analysis of the example structure subject to earthquake excitation was conducted in the reinforcement learning procedure. Deep Q-network (DQN) among various reinforcement learning algorithms was used to make a learning agent. The command voltage sent to the MR damper is determined by the action produced by the DQN. Parametric studies on hyper-parameters of DQN were performed by numerical simulations. After appropriate training iteration of the DQN model with proper hyper-parameters, the DQN model for control of seismic responses of the example structure with smart TMD was developed. The developed DQN model can effectively control smart TMD to reduce seismic responses of the example structure.

• Structural Engineering and Mechanics
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• 제30권1호
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• pp.1-20
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• 2008

The dynamic characteristics of the passive, semi-active, and active tuned-liquidcolumn dampers (or TLCDs) are studied in this paper. The design of the latter two are based on the first one. A water-head difference (or simply named as water head in this paper) of a passive TLCD is pre-set to form the so-called semi-active one in this paper. The pre-set of water head is released at a proper time instant during an earthquake excitation in order to enhance the vibration reduction of a structure. Two propellers are installed along a shaft inside and at the center of a passive TLCD to form an active one. These two propellers are driven by a servo-motor controlled by a computer to provide the control force. The seismic responses of a five-story shear building with a passive, semiactive, and active TLCDs are computed for demonstration and discussion. The responses of this building with a tuned mass damper (or TMD) are also included for comparison. The small-scale shaking-table experiments of a pendulum-like system with a passive or active TLCD to harmonic and seismic excitations are conducted for verification.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 추계학술대회 논문집
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• pp.82-83
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• 2011