Session: SE-02-01 Seismic Isolation

Paper Number: 152063

152063 - Theory of Floating Seismic Isolation System 

Abstract: 

Floating nuclear power plants have been studied and, in some cases, deployed as marine systems. Although horizontal seismic waves may be naturally isolated from the floating plant due to little transfer of shear forces in water, the vertical component can propagate through the water to the plant from the seafloor in a phenomenon called “seaquake”.

Recently, a concept of floating seismic isolation system (FSIS) has been proposed. The FSIS is a unique seismic isolation mechanism with a number of cavities and orifices embedded in the bottom of the floating structure. The cavity is designed to reduce peak vibration response of the structure by vertical seismic input, while the orifice is used to add damping for residual vibration reduction.

This paper presents the theory of seismic isolation of the FSIS. The governing equations of motion are derived. The analytical solutions of the equations of motion are obtained. The solutions presented herein point out the quantitative evidence of the seismic isolation of the FSIS and identify the principal variables of the floating vibration body, such as the frontal area of ​​the cavities and the damping of the orifice, which determine the seismic reduction potential of the FSIS. This paper shows the potential of the seismic isolation effect of the FSIS.

Presenting Author: Takashi Mori IHI Corporation

Presenting Author Biography: The author obtained a Master's degree from Kyoto University Graduate School. Since 2018, he has been working at IHI Corporation, where he has been engaged in the seismic evaluation and development of base isolation devices for cranes and unloaders used in nuclear and coal-fired power plants, utilizing advanced seismic and base isolation technologies.

Authors:

Takashi Mori IHI Corporation
Takahiro Shimada IHI Corporation
Xing L Yan Japan Atomic Energy Agency