Dependence of Horizontal Vibration Characteristics on Load Weight Distribution in Magnetic Levitation Type Seismic Isolation Device

We have developed a magnetic levitation type seismic isolation device. The device could remove any horizontal vibrations very effectively. Three-layer structure was adopted in the device. The bottom layer was composed of permanent magnets. The middle layer comprised HTS bulks and permanent magnets. The top layer consisted of HTS bulks. The horizontal vibration characteristics in the middle layer depended on the air gap between the bottom and middle layers; the air gap was closely related to the load weight distribution in the top and middle layers. Inhomogeneous load weight distribution caused the different air gap in each bulk. Horizontal levitation against the inhomogeneous load weight distribution, however, could be obtained by adjusting the initial offset angle of each bulk in field-cooling process. The smaller initial air gap was effective in realizing horizontal levitation; the difficulty of horizontal levitation increased with the initial air gap. Independent of the load weight distribution, almost the same characteristics of horizontal vibration were obtained in the small initial air gap.