VERTICAL SEISMIC ISOLATION DEVICE USING CONSTANT LOAD SUPPORTING MECHANISMS

Abstract

We present a vertical seismic isolation device for limiting the response acceleration less than a specified value. In Japan, strong near-fault earthquakes have been recorded frequently in recent years. And the demand is increasing for developing vertical seismic isolation devices to protect important objects. In vertical seismic isolation, large deformation due to gravity takes place if the seiffness is simply reduced. To overcome this difficulty, we use constant-load springs, which sustain constant load regardless of displacement. Since the object placed on the device is supported only by constant-load springs, transmission of the reaction force can be limited within a specified value. This way, the peak response acceleration of the object can be controlled regardless of the kinds and magnitudes of earthquake ground motions. This paper demonstrates the effectiveness of the present vertical seismic isolation device thorough experiments and simulations.