A Semi-Active Control Algorithm for Base-Isolated Structures

The possibility of enhancing the seismic structural response of base-isolated (BI) structures through the adoption of additional smart damping devices has been widely investigated in literature for many years. However, few experimental data are available on this subject. The proposed paper describes a research activity about the adoption of semi-actively (SA) controlled magnetorheological (MR) dampers in BI buildings. First, a control algorithm able to “re-shape” structural modes, frequencies and damping ratios is introduced in the paper and specialized to the case of BI structures with additional control devices. Then a clipped version of the proposed control algorithm is shown to be utilized in conjunction with SA MR dampers. An experimental mock up made up of a BI 1-story steel frame is then described. The main results of the seismic experimental tests on a shaking table are presented and commented.