This dissertation proposes simple and efficient control algorithms for seismically excited structures using MR dampers and a smart passive system based on MR dampers. Magnetorheological (MR) dampers are one of the most promising control devices for civil engineering applications to earthquake hazard mitigation, because they have many advantages such as small power requirement, reliability, and low price to manufacture.
A number of control algorithms have been adopted for semiactive systems including the MR damper. In spite of good features of previous studies, some algorithms have drawbacks such as poor performances or difficulties in designing the weighting matrix of the controller. Thus, the control algorithm is required, which is simple to use and efficient to give comparable or better performance over the previous algorithms.
As a simple and efficient control algorithm, a modal control scheme and a maximum energy dissipation algorithm (MEDA) are implemented for the MR damper-based control system.
Modal control reshapes the motion of a structure by merely controlling a few selected vibration modes. Hence, a modal control scheme is more convenient to design the controller than other control algorithms. Although modal control has been investigated for the several decades, its potential for a semiactive control, especially for the MR damper, has not been exploited. Thus, in order to study the effectiveness for the MR damper system, a modal control scheme is implemented to seismically excited structures. A Kalman filter is included in a control scheme to estimate modal states from physical measurements by sensors. Three cases of the structural measurement are considered as a feedback to verify the effect of each measurement; displacement, velocity, and acceleration, respectively. Moreover, a low-pass filter is applied to eliminate the spillover problem. In a numerical example, a six-story building model with the MR dampers on the bottom two floors is used to ...