Shaking table tests to compare semi-active control algorithms for variable dampers

The authors present and discuss the main results of a experimental campaign performed on a near full-scale semi-actively controlled steel building, in the framework of a research program financed by the Italian Department of Civil Protection. Four control algorithms have been investigated through shaking table tests under seven different natural earthquakes. They belong to the family of control algorithms based on a sound physical sense, where semi-active devices are typically seen as smart damping devices for which the amount of dissipation can be quickly regulated: usually they require less measurements, which often are made in the close surroundings of the device; therefore, the computational effort is fairly moderate and, in principle, it could be sustained by small, battery-powered computing systems. After a literature review on semi-active control algorithms, the paper first summarizes the logic behind the ones adopted in the tests. Then a direct comparison among them is done on the basis of the results gained from the tests. Each of the control logics has been evaluated and compared each other in terms of effectiveness in the reduction of interstorey drifts and of amount of dissipated energy, leading to comments may be useful for the design of a semiactive control strategy based on the use of such kind of variable devices.