Experimental study of active control for MDOF seismic structures

Active control of building structures has been extensively studied theoretically, using a variety of control schemes showing varying degrees of efficiency. The demand for experimental evidence of feasibility of control of structures subjected to severe transient loads leads to the present study. Structural control experiments are carried out in the laboratory using a 1:4-scaled model structure simulating a three-story frame building. The control experiments are performed using a system of prestressing tendons connected to a servo-hydraulic system and linear optimal control algorithms. The model is subjected to base motions produced by a 12 ft x 12 ft (3.6 m x 3.6 m) shaking table, which include banded white noise and earthquake accelerograms. Results of the experiments show clearly that traditional algorithms can be implemented when proper adjustments are made. These include compensations for time delay and error accumulation in the online computation. Several new algorithms based on instantaneous optimal control are experimentally verified in this study, following new developments based on previous experiments of single-degree-of-freedom structures. The efficiency of various algorithms is discussed along with comparisons of analytical and experimental results.