• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.899-900
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• 2011

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2006년도 학술발표회 논문집
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• pp.503-510
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• 2006

Seismic control performance of MR dampers, which have severe nonlinearity, differs with respect to the dynamic characteristics of an earthquake such as magnitude, frequency and duration. In this study, the effects of excitation characteristics on the equivalent linear system of a building structure with an MR damper are investigated through numerical analysis for artificial ground motions generated from different response spectrums. The equivalent damping ratio of the structure with an MR damper is calculated using Newmark and Hall's equations for ground motion amplification factors. It is found that the equivalent damping ratio of the structure with the MR damper is dependent on the ratio of the maximum friction force of the MR damper over excitation magnitude. Frequency contents of the earthquake ground motion affects the equivalent damping ratio of long-period structures considerably. Also, additional damping effect caused by interaction between the viscousity and friction of the MR damper is observed.

• 한국지진공학회논문집
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• 제9권2호통권42호
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• pp.7-15
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• 2005

본 연구에서는 하이브리드 면진장치가 설치된 단자유도 구조물의 동적거동을 예측할 수 있는 수치해석모델을 제안한다. 하이브리드 면진장치는 MR 감쇠기와 마찰진자시스템(FPS)으로 구성된다. MR감쇠기의 동적거동을 모형화하기 위하여 뉴로-퍼지 모델을 사용한다. 다양한 변위, 속도, 전압의 조합을 사용하여 MR 감쇠기의 성능실험을 수행한 후 얻어진 데이터를 이용하여 MR 감쇠기 뉴로-퍼지 모델을 ANFIS로 학습시킨다. FPS의 모형화는 본 연구에서 유도한 비선형 모델식에 근거하여 뉴로-퍼지 모형화방법을 사용하여 이루어진다. 본 연구에서는 MR 감쇠기로 전달되는 제어전압을 조절하기 위하여 퍼지논리제어기를 사용한다. 다양한 지진하중을 사용한 진동대 실험을 통하여 얻은 실험체의 동적응답과와 뉴로-퍼지 모형화방법을 사용한 수치해석의 결과를 비교한다. 뉴로-퍼지 모델을 사용하여 MR 감쇠기와 FPS를 모형화해서 수치해석을 수행한 결과 하이브리드 면진장치의 동적거동을 매우 정확하게 예측할 수 있었다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.459-464
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• 2007

Seismic control performance of MR dampers, which have severe nonlinearity, differs with respect to the dynamic characteristics of an earthquake such as magnitude, frequency and duration. In this study, the effects of excitation characteristics on the equivalent linear system of a building structure with the MR damper are investigated through numerical analysis for artificial ground motions generated from different response spectrums. The equivalent damping ratio of the structure with the MR damper is calculated using Newmark and Hall's equations for ground motion amplification factors. It is found that the equivalent damping ratio of the structure with the MR damper is dependent on the ratio of the maximum friction force of the MR damper over excitation magnitude. Frequency contents of the earthquake ground motion affects the equivalent damping ratio of long-period structures considerably. Also, additional damping effect caused by interaction between the viscousity and friction of the MR damper is observed. Finally, response reduction factors for equivalent linear systems are proposed in order to improve accuracy in the prediction of the actual nonlinear response.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.879-885
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• 2006

Seismic control performance of MR dampers, which have severe nonlinearity, differs with respect to the dynamic characteristics of an earthquake such as magnitude, frequency and duration. In this study, the effects of excitation characteristics on the equivalent linear system of a building structure with the MR damper are investigated through numerical analysis for artificial ground motions generated from different response spectrums. The equivalent damping ratio of the structure with the MR damper is calculated using Newmark and Hall's equations for ground motion amplification factors. It is found that the equivalent damping ratio of the structure with the MR damper is dependent on the ratio of the maximum friction force of the MR damper over excitation magnitude. frequency contents of the earthquake ground motion affects the equivalent damping ratio of long-period structures considerably. Also, additional damping effect caused by interaction between the viscousity and friction of the MR damper is observed. Finally, response reduction factors for equivalent linear systems are proposed in order to improve accuracy in the prediction of the actual nonlinear response.

• 한국소음진동공학회논문집
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• 제18권1호
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• pp.87-93
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• 2008

Seismic control performance of MR dampers, which have severe nonlinearity, varies with respect to the dynamic characteristics of an earthquake such as magnitude, frequency and duration. In this study, the effects of excitation characteristics on the equivalent linear system of a building structure with the MR damper are investigated through numerical analysis for artificial ground motions generated from different response spectrums. The equivalent damping ratio of the structure with the MR damper is calculated using Newmark and Hall's equations for ground motion amplification factors. It is found that the equivalent damping ratio of the structure with the MR damper is dependent on the ratio of the maximum friction force of the MR damper over excitation magnitude. Frequency contents of the earthquake ground motion affects the equivalent damping ratio of long-period structures considerably. Also, additional damping effect caused by interaction between the viscousity and friction of the MR damper is observed. Finally. response reduction factors for equivalent linear systems are proposed in order to improve accuracy in the prediction of the actual nonlinear response.

• 한국소음진동공학회논문집
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• 제20권11호
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• pp.1046-1051
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• 2010

This paper presents design and performance evaluation of magnetorheological(MR) damper for integrated isolation mount. The MR damper needs two functions for the integrated isolation mount. The one is vibration absorption and the other is isolation of vibration transmission. For vibration absorption, the MR damper requires wide damping force range. And for isolation of vibration transmission, the friction of MR damper needs to be eliminated. In order to achieve this goal, a novel type of MR damper is originally designed in this work. Subsequently, the MR damper is mathematically modeled and its damping force characteristics are evaluated. In addition, the vibration control performance of the MR damper associated with the stage mass is evaluated. From the result, this paper evaluates the performance of MR damper for integrated isolation mount.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2006년도 학술발표회 논문집
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• pp.511-518
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• 2006

In this study, seismic response mitigation effect of an MR damper generating response-dependent frictional force is investigated. It has been reported in previous studies that passively operated MR damper with constant input current doesn't show better control performance than semi-active MR damper with varying input current calculated by control algorithms such as linear quadratic regulator and sliding mode control. However, in order to operate the MR damper semi-actively, other control systems besides the damper itself such as sensors for measuring structural responses and controller for calculating optimal input current are necessary, which deteriorate the economical efficiency. This study presents a MR damper generating frictional force of which magnitude is controlled in accordance to the displacement and velocity transferred to the damper. Numerical analyses results indicate that the performance of the response dependent MR damper is closely related with the range of the friction force and it can be designed to short better control performance than the passive MR damper.

• Smart Structures and Systems
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• 제6권8호
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• pp.953-974
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• 2010

The performance of variable dampers for seismic protection of the benchmark highway bridge (phase I) under six real earthquake ground motions is presented. A simplified lumped mass finite-element model of the 91/5 highway bridge in Southern California is used for the investigation. A variable damper, developed from magnetorheological (MR) damper is used as a semi-active control device and its effectiveness with friction force schemes is investigated. A velocity-dependent damping model of variable damper is used. The effects of friction damping of the variable damper on the seismic response of the bridge are examined by taking different values of friction force, step-coefficient and transitional velocity of the damper. The seismic responses with variable dampers are compared with the corresponding uncontrolled case, and controlled by alternate sample control strategies. The results of investigation clearly indicate that the base shear, base moment and mid-span displacement are substantially reduced. In particular, the reduction in the bearing displacement is quite significant. The friction and the two-step friction force schemes of variable damper are found to be quite effective in reducing the peak response quantities of the bridge to a level similar to or better than that of the sample passive, semi-active and active controllers.

• 한국지진공학회논문집
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• 제9권1호통권41호
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• pp.61-70
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• 2005

본 연구에서는 하이브리드 면진장치가 설치된 단자유도 구조물에 대하여 진동대 실험을 수행하였다. 본 연구에서 사용된 하이브리드 면진장치는 네 개의 FPS와 한 개의 MR 감쇠기로 구성하였다. 다양한 크기 및 특성을 가진 지진하중을 하이브리드 면진장치가 설치된 구조물에 가하여 진동제어 성능을 평가하였다. 본 연구에는 준능동 MR 감쇠기의 저항력을 효과적으로 조절하기 위하여 퍼지제어기를 사용하였고 구조물에 부착된 계측기를 통하여 변위 및 가속도를 피드백으로 이용한다. 수동 및 준능동 제어기법을 사용하여 얻은 구조물의 응답을 서로 비교하였고 그 결과 FPS와 MR 감쇠기의 조합으로 다양한 특성의 하중을 받는 구조물의 진동제어를 효과적으로 수행할 수 있음을 알 수 있다.