A comparative analytical study of several control strategies for semi-active(SA) devices installed in baseisolated buildings aiming to reduce earthquake induced vibrations is presented.Three force tracking schemes comprising a linear controller plus a “clipped” algorithm and a nonlinear output feedback controller(NOFC) are considered to tackle this problem.Linear controllers include the integral controller(I),the linear quadratic regulator(LQR) and the model predictive controller(MPC).A single degree-of-freedom system subjected to input accelerograms representative of the Portuguese seismic actions are first used to validate and evaluate the feasibility of these strategies.The obtained results show that structural systems using SA devices can in general outperform those equipped with passive devices for lower fundamental frequency structural systems,namely base-isolated buildings.The effectiveness of the proposed strategies is also evaluated on a 10 storey base-isolated dual frame-wall building.The force tracking scheme with an integral controller outperforms the other three as well as the original structure and the structure equipped with passive devices. A comparative analytical study of several control strategies for semi-active (SA) devices installed in baseisolated buildings aiming to reduce earthquake induced vibrations is presented. Three force tracking schemes includes a linear controller plus a “clipped” algorithm and a nonlinear output feedback controller (NOFC) are considered to tackle this problem. Linear controllers include the integral controller (I), the linear quadratic regulator (LQR) and the model predictive controller (MPC). A single degree-of-freedom system subjected to input accelerograms representative of the Portuguese seismic actions are first used to validate and evaluate the feasibility of these strategies. The resulting results show that structural systems using SA devices can in general outperform those equipped with passive devices for lower fundamental frequency structural systems, that base-isolated buildings. The effectiveness of the proposed strategies is also evaluated on a 10 storey base-isolated dual frame-wa ll building.The force tracking scheme with an integral controller outperforms the other three as well as the original structure and the structure equipped with passive devices.