A New Algorithm of Semi-active Friction Dampers for Structures under Earthquakes

A new algorithm of semi-active friction dampers (SAFD) is proposed in this paper for controlling the seismic responses of structures, based on the linear quadratic regulator (LQR) control theory. In order to numerically verify the control effectiveness of the proposed algorithm, the time history analysis has been implemented to a seismically excited 3-storey frame structure with the friction dampers (FD). In the numerical simulations, five seismic waves, namely El Centro wave, Hachinohe wave, Kobe wave, Taft wave, and Shanghai artificial wave are taken into consideration, whose peak accelerations are scaled to 0.1 gal and 0.3 gal, respectively. For the purpose of comparison, the numerical results of the 3-storey frame structure with dampers designed by general semi-active damper control algorithm (referred herein to as the SADCA) are also taken into account. Numerical results demonstrate that the proposed semi-active control algorithm is better than the SADCA under the present five seismic waves. Especially, this new semi-active control algorithm will render higher level of the acceleration response reduction for higher floors of structures under earthquakes.