Developing LH Controller to Model Low- and High-Velocity Behavior in a Prototype MR Damper.

A low- and high-velocity based controller (LH controller) is developed to model the force-velocity relationship of a magnetorheological (MR) fluid damper that enables the controlling current to be calculated as a function of required control force. The proposed bilinear force-velocity model predicts the high-velocity region as well as the often neglected low-velocity region that corresponds to the damper responses in the postyield and preyield regions, respectively. The calculated current may then be supplied to an experimentally parameterized prototype small-capacity MR damper (50 kN) to control seismic responses at a lower cost. Numerical examples are used to demonstrate the ability of the LH controller to reduce structural displacements and accelerations in comparison with three other state-of-the-art controllers, namely, the clipped optimal controller, modified clipped optimal controller, and inverse model, which neglect the low-velocity region of the damper. After including this region, the LH controller significantly lowers peak accelerations by 57.7, 33.4, and 13.0%, respectively, over the three other common controllers and also lowers mean displacements by 85.9, 81.7, and 85.4%, respectively. Lastly, the LH controller is used to reduce the peak drifts and accelerations in comparison with those of a 20-story benchmark building. [ABSTRACT FROM AUTHOR]