Fundamental Study on the Super-Long-Period Active Isolation System Available to Purchase

Since the Hanshin-Awaji Earthquake Disaster, the number of isolated structures has been greatly increased. The natural period of the isolation system is designed around 3 seconds, because predominate period of observed seismic waves is usually 0.1 to 1 second. However, relatively long period seismic waves have been observed in various earthquakes, and the resonance of long-period structures, such as high-rise buildings, during earthquakes have been reported at the same time. Therefore the natural period needs to be extended. When extending the natural period of the isolated structure using rubber bearings, its stiffness needs to be reduced. It is more difficult to extend the natural period of the isolation system than the conventional system because of its buckling problem. Therefore we propose a super-long-period active seismic isolation system as a new method for extending the natural period of the isolated structure. This system consists of rubber bearings and actuators. In this study, we designed a control system by using the model-matching-method. This is one of the classical control system design methods. We investigated the isolation performance by numerical analysis. In addition, we selected the optimal variables of transfer function using genetic algorithm.