Development of vertical vibration isolation device with specified

Verification of vibration isolating effect through numerical

Abstract

This paper presents a vertical vibration isolation device (VVID), which can reduce the maximum response acceleration of the target object to a specified value regardless of the kinds of earthquake ground motions. We demonstrate the effectiveness of the present VVID through numerical simulations. Vertical vibration isolation is much more difficult than horizontal one because of the existence of gravity. To resolve this difficulty, we use a combination of constant load springs, which sustain constant load regardless of the magnitude of deformation. With the effective use of the springs in conjunction with gravity, we realize a resisting mechanism that gives a downward constant force to the target object when it moves up from the reference (static equilibrium) state and an upward one when moves down. This mechanism enables the VVID to limit the transmission of the reaction force to the target object within the specified value, and to realize the vibration isolation effect that does not depend on earthquake ground motions. Moreover, the VVID can avoid resonance.