In this paper, the authors have developed a new type of horizontal seismic isolation table which has large effect of vibration isolation for ordinary earthquakes and suppresses the resonance of the isolation system due to long-period seismic ground motions. The seismic isolation table is composed of a table board, X-Y rails, a baseboard, four coil springs which are attached perpendicular to the four sides of the table board and two constant-hardening type friction dampers which are attached along the X and Y rails. The trial seismic isolation table was made, and the effects of vibration suppression of the isolation table were discussed experimentally and numerically. The experimental and calculated results showed that the isolation table using four coil springs and two constant-hardening type friction dampers is effective for suppressing the vibration of an isolation table caused both by ordinary and long-period seismic ground motions.
