NEHRP Clearinghouse

Semi-Active Control Algorithms for Structures with Variable Dampers.
Sadek, F.; Mohraz, B.
October 1997, 50 p.
Identifying Number(s)
Semi-active control systems combine the features of active and passive control to reduce the response of structures to various dynamic loadings. They include: (1) active variable stiffness where the stiffness of the structure is adjusted to establish a non-resonant condition, and (2) active variable damper where the damping coefficient of the device is varied to achieve the most reduction in the response. This study is concerned with examining the effectiveness of variable dampers for seismic applications. Three algorithms for selecting the damping coefficient of variable dampers are presented and compared. They include: a linear quadratic regulator (LQR) algorithm, a generalized LQR algorithm where a penalty is imposed on the acceleration response, and a displacement-acceleration domain algorithms where the damping coefficient is selected by representing the response as a point on the displacement-acceleration plane.
; Buildings; Earthquake engineering; Seismic design; Vibration damping; Algorithms; Accelerometers; Design; Dynamic structural analysis