Implication of higher mode for dynamic soil structure interaction of offshore wind turbine

Abstract

The construction and popularity of multimegawatt offshore wind turbines (OWTs) are increasing globally because of their capacity to produce clean and green energy at a low cost. As many of these structures will continue to be installed in earthquake prone areas worldwide, it becomes necessary to develop a better understanding of the dynamic soil-structure interaction (DSSI) particularly the higher mode effects involved in the dynamic response. The main aim of this study is to perform a rigorous modal analysis of the NREL 5MW offshore wind turbine using several monopile foundation modeling techniques to show the higher mode effects. Furthermore, the different parameters such as diameter and embedded depth of the monopile and soil initial moduli affecting the dynamic characteristics are investigated. The study shows that higher modes need to be considered in order to obtain a more rational dynamic soil-structure interaction response of the system.