Abstract
In order to design the seismic isolators in buildings, the transfer function of the vibration from the ground to the floor should be considered. This paper deals the horizontal and vertical transfer function of buildings. Besides, a three dimensional seismic isolator considering the transfer function of buildings is also proposeed. In order to have both a low stiffness and a high allowable load in the vertical direction, a negative stiffness mechanism is used in the seismic isolators.