3D Modeling of Long-Term Dynamic Behavior of Monopile-Supported Offshore Wind Turbine in Clay

Abstract

This article outlines the long-term dynamic behavior of the monopile-supported offshore wind turbine (OWT) in clay. A three-dimensional (3D) finite-element (FE) model was developed that uses viscoelastic material constitutive models for soils in conjunction with stiffness-degradation functions to examine the long-term behavior of monopile-supported OWTs subjected to transient loading. The proposed numerical model was validated by experimental results and recorded data from real offshore wind turbines. Effects of amplitudes of wind and wave loads and their frequency, monopile length and diameter, and rotor-nacelle assemble (RNA) mass on the long-term dynamic behavior of a 5-MW OWT due to different load cycles were studied. The results show that the effect of wind load governs the design and that monopile diameter has a significant role in the long-term behavior of the structure.