Semiactive structural-control based on variable slip-force level dampers

This paper presents a semiactive control strategy based on variable slip-force level dampers. The proposed scheme controls only the slip-force level of the friction damper in such a way that the damper exhibits bilinear hysteresis with a ductility factor equal to two regardless of the level of seismic excitation. With a constant ductility factor maintained in any seismic event, the damper behaves like a linear system in response to any seismic excitation. For implementation of this scheme in multistory buildings, an autonomous-decentralized type of control system is constructed. In such a control system, a number of subcontrol systems are present, each of which is controlled by the decentralizing or local controller utilizing local response information. The fundamental idea is first presented through the application of this control scheme to a single-degree-of-freedom structure. The extension of the scheme to a multistory building structure is then discussed. Finally, the feasibility of utilizing oil dampers for the proposed control strategy is experimentally examined.