Experiments on active control of seismic structures

This paper presents the first phase of a comprehensive experimental study concerning the possible application of active control to structures under seismic excitations. In the laboratory, a singledegree- of-freedom model structure was used which was controlled using prestressing tendons connected to a servohydraulic actuator. An optimal closed-loop control scheme using a quadratic performance index was employed to reduce the response of structure under base motion generated by a large-scale seismic simulator. The time delay between the observed motion and the implemented control forces, an important factor in control implementation, was integrated in the control algorithm. Using a carefully designed, fabricated, and calibrated experimental setup, the correlation between the analytical and experimental results was studied. Based on similitude relations, the experimental results obtained for the model structure were extrapolated to the full-scale structures and are analyzed.