Optimal control of MDOF structures with controlled stiffness dampers

The structure and application of supplemental controlled stiffness dampers are discussed. The instantaneous and the polynomial active control theories are used to obtain the control forces at each time step during an occurring earthquake. The efficiency of these control strategies in a structure with the controlled stiffness dampers is compared. Control of the damping forces is enabled due to the mechanical structure of the damper, which is described in the paper. This device can be efficiently used as a structural damper because the forces developed in it are independent of the structure's displacements or velocities. The efficiency of the damper is demonstrated in a numerical simulation of a seven-story building. The simulation shows that the behavior of a structure with the active controlled stiffness dampers was significantly improved compared to that of an uncontrolled structure, and of a passive controlled viscous damped structure, subjected to the same earthquakes.