Semi-active control of building structures using MR dampers based on a modified inverse dynamic model

Thesis (M.S.)--University of Hawaii at Manoa, 2008.Includes bibliographical references (leaves 66-71).xi, 79 leaves, bound 29 cmThis thesis presents a new semi-active strategy to adjust the voltage of a magnetorheological (MR) damper to track the optimal/desired damper force by the Linear Quadratic Regulator (LQR) method. Integrated with the new strategy, a modified inverse dynamic model is proposed to evaluate the value of evolutionary variable z. The new strategy is applied to numerical examples including one-story buildings with different periods (stiff, moderate and flexible). White Gaussian noise (WGN) and 1940 El Centro earthquake are chosen as excitations. The numerical results indicate that this new strategy is effective and practically implementable in reducing the structural responses under various excitations. Furthermore, its effectiveness in structural control of buildings is compared with passive-on and passive-off cases. In addition, various factors that influence the MR damper's performance, including control force weighting coefficient R, periods of buildings, types of excitation and its amplitude, are presented and discussed. And an appropriate way to choose R is also recommended. Finally, this strategy is numerically applied to a six-story building model. The results show that the MR damper also performs well in vibration control of multi-story buildings