Skyhook-based monitoring and control of a steel building under seismic action

Sky-hook damping is one of the most promising techniques for feedback control of structural vibrations. It is based on the idea of connecting the structure to an ideal fixed point of the space through passive dissipative devices. Herein the benefit of semi-active (SA) sky hook (SH) damping is investigated for seismic protection of a two-story steel frame via shaking table tests. This kind of SA control is achieved implementing a continuous monitoring of selected structural response parameters and using variable dampers. The damping properties of the latter are changed in real-time so as to make the force provided by the damper match the desired SH damping force as closely as possible. To this aim, two prototype magnetorheological dampers have been installed at the first level of the frame and remotely driven by a SH controller. The high effectiveness of the control strategy is proved comparing the floor accelerations and interstory drift in both uncontrolled and controlled configurations. Practical issues about the implementation of the measurement system needed for the monitoring activity are finally discussed.