Seismic simulation test of equipment protection by using a fuzzy-controlled smart isolation system

Vibration-sensitive equipment mounted on a building structure can be severely damaged by a moderate earthquake, due to the dynamic amplification effect of the primary structure. To alleviate this problem, the seismic protection of such equipment using a fuzzy-controlled piezoelectric equipment isolation system (PEIS) is investigated experimentally in this study by conducting a shaking table test. In the test, the PEIS is placed on top of a full-scale steel frame that is used to simulate the dynamic effect of the primary structure, while the mass of the equipment on the PEIS is simulated by rigid mass blocks. Through controlling the driving voltage of the embedded piezoelectric actuator, the friction damping and motions of the PEIS are attenuated by the fuzzy controller. The implementation of the proposed fuzzy-controlled system requires only one displacement sensor, and thus the system is very easy to implement and less costly than comparable systems. The results of the experiment suggest that, for earthquakes with high intensities or strong near-fault characteristics, the studied system is able to substantially reduce the demand for isolation displacement while maintaining superior isolation efficiency. This implies that the proposed system is particularly desirable for cases of equipment isolation in which the installation space is limited.