구조물의 성능을 개선하기 위하여 다양한 진동제어장치가 사용되고 있다. 대부분의 제진장치는 구조물의 감쇠비를 증가시킴으로써 성능개선효과를 유도하기 때문에 증가된 감쇠비는 제진장치에 의한 구조물의 성능을 평가하는 중요한 지표가 될 수 있다. 본 연구에서는 강풍 등으로 제진장치가 운영 중인 상태에서 구조물의 응답만을 이용하여 각 모드에 증가된 등가감쇠비를 추정하는 프로세스를 개발하고 이를 성능개선효과를 평가하는데 활용하고자한다. 제진장치가 설치된 구조물은 비고전 감쇠시스템이므로 상태공간 모드분해법을 이용하여 계측응답으로부터 모드 응답을 구하고, 분해된 모드응답에 가상 동적 진동기를 적용하여 각 모드에 증가된 감 쇠비를 구하였다. 제안된 제진장치 설치 구조물 감쇠비 추정법을 검증하기 위하여 수동형 제진장치로 카고메 점탄성 댐퍼를, 능동형 제진장치로 능동질량감쇠기를 구조물에 적용하여 각 제진장치에 의한 감쇠비를 추정한 결과 매우 정교하게 예측 가능함을 알 수 있었다.

Seismic control performance of MR dampers, which have severe nonlinearity, is different with respect to the dynamic characteristics of earthquake excitations such as magnitude and frequency contents. In this study, effects of excitation characteristics on the equivalent linear system represented by an equivalent damping ratio for single-degree-of-freedom (SDOF) systems with a MR damper are investigated through numerical analysis for various natural frequencies of the structures and design parameters of the MR damper. In addition, to implement the an equivalent linearization procedure considering non-stationarity and frequency contents of the earthquake excitation, seismic response reduction factors for artificial earthquake ground motions are proposed using regression analysis of the linear structural responses. Analysis results show that the relative magnitude of the excitation compared to the friction force of the MR damper and frequency contents of the excitation affect the equivalent damping ratio considerably, and appropriate combination of friction and damping produces additional damping effect

The purpose of this study is to propose the general method for evaluating the equivalent damping ratios of a structure with supplemental response control dampers. We define Lyapunov function of which derivative can be expressed in autoregressive form and evaluate the equivalent damping ratios by using Lyapunov function and its derivative. This Lyapunov function may be called as generalized structural energy. In this study, it is assumed that the response of a structure is stationary random process and control dampers do not affect the modal shapes of a structure, and the structure has proportional damping. Proposed method can be used to get the equivalent damping ratios of a structure with non-linear control dampers such as friction dampers as well as linear control dampers. To show the effectiveness of the proposed method, we evaluate the equivalent damping ratios of a structure with viscous dampers, AMDs, and friction dampers. The equivalent damping ratios from proposed method are compared to those from eigenvalue analysis for linear control dampers, and those from time history analysis for non-linear control dampers, respectively.