PERFORMANCE EVALUATION OF AN MR DAMPER IN BUILDING STRUCTURES CONSIDERING SOIL-STRUCTURE INTERACTION EFFECTS.

Since the force generated by a magneto-rheological (MR) damper has large nonlinearity, the performance of an MR damper is dependent on response characteristics such as frequency and amplitude. Soil-structure interaction (SSI) is generally known to have a large effect on the seismic response of a building structure. In this study, the performance of an MR damper in mitigating the seismic response of a building structure is evaluated considering the SSI effects. First, the performance variance of an MR damper due to the change of the structural natural period is investigated by constructing its normalized response spectrum through the numerical analysis of many earthquake wave records and the natural period of a structure. The variable friction force of an MR damper is normalized by the structural base shear force, and its amplitude and decrement of response are quantitatively evaluated. Then, the response characteristics of the SSI system due to the lengthening of the structural natural period and various soil conditions are numerically evaluated based on the response spectrum analysis. Finally, the numerical results with and without considering the SSI effects are comparatively evaluated for the building structure with an MR damper. The comparison results show that the SSI effect should be considered in order that the undesirable effect of an MR damper on the structural control would not be neglected. [ABSTRACT FROM AUTHOR]