Seismic isolation control for a building-like structure

Minimizing the damage to buildings from large earthquakes is very important in maintaining urban function, especially if buildings contain critical facilities. Although passive isolation systems have been used in civil structures, if earthquakes of such great magnitude occur these systems are ineffectual, an active seismic isolation system may be useful. The article discusses the design method of an active vibration isolator for a multi-degree-of-freedom structure such as a tall building. The controlled variables are selected based on minimization of interaction between a controlled structure and its base. The controller design employs the well-known μ-synthesis approach-considered one of the most robust control methods for parameter variations of the controlled structure. Based on experiments on our laboratory structure and on simulations of an actual building, a controller is designed for an active vibration isolator whose passive elements are installed in parallel with the active element. We show that the proposed design method is useful for seismic isolation of tall buildings.