EXPERIMENTAL STUDY ON SEISMIC CONTROL EFFECT DUE TO LIQUID MOTION AROUND MONOPILE TYPE FOUNDATION OF OFFSHORE WIND TURBINE WITH UNDERWATER SESMIC CONTROL PANEL

Abstract

 The authors have proposed a seismic control structure in which a larger cylindrical underwater seismic control panel is partially submerged around the monopile foundation of an offshore wind turbine. This structure is expected to reduce the seismic cross-sectional force generated in the monopile by the interaction with water during vibration, and its effectiveness has been confirmed by underwater shaking table tests. However, the mechanism of seismic control has not been fully clarified. In this study, we focused on the liquid motion of water between the underwater seismic control panel and the monopile as one of the seismic control mechanisms, and conducted shaking table tests around the seismic control plate to investigate the vibration characteristics due to the liquid motion. From the results, it was clarified that the fluid force due to the liquid motion contributes to the seismic resistance and this force can be modeled by a mass point, a spring and a damper in the numerical analysis.