Analysis of capability for semi-active or passive damping systems to achieve the performance of active control systems

Linear quadratic regulator (LQR)-based control force is composed of an elastic restoring force component and a damping force component. According to the analysis of the proportions of the elastic restoring force and the damping force to the total active control force, two indices are defined to quantify the damping characteristics and negative stiffness characteristics of an active control force. Because a semi-active damping system behaves like a damping device with adjustable parameters, these two indices can be used to quantify the capability of a semi-active damping system and a passive damping system achieving the performance of a fully active control system. Numerical studies are conducted to investigate the damping characteristics and negative stiffness characteristics of an active control force in an active control system. Semi-active damping systems and passive damping systems are designed to replace the active control systems and then the capability of the semi-active control and passive control achieving the performance of fully active control is further studied through the numerical study. Finally, the negative stiffness characteristics realized by semi-active magnetorheological (MR) damping systems are demonstrated through an in situ field test of a stay cable in the Binzhou Yellow River Highway Bridge. Copyright (C) 2010 John Wiley & Sons, Ltd.