A seismic isolation floor using a new mechanism to achieve high performance in vertical isolation, was developed. The floor was a partially 3-dimensional isolation floor in which a vertical isolation table was incorporated in a horizontal 2-dimensional isolation floor. The table was suspended from pulleys by wire cables which were connected to coil springs installed horizontally. This mechanism was used to convert vertical movements of the table into horizontal deformations of the springs, and made it possible to provide the table with a very low natural frequency of 0.5 Hz or so. Excitation tests were carried out for an experimental model of the floor on which a computer component was mounted. Through the tests, it was confirmed that the floor had excellent performance in vertical isolation as well as in horizontal isolation. Analytical models for the horizontal and vertical responses of the floor were supported by the experimental results.
