Effect of monopile foundation modeling on the structural response of a 5-MW offshore wind turbine tower

Offshore wind turbine towers experience large base moments because of wind and wave loading. The flexibility of the foundation should be considered when analyzing the structural response of towers. Previous studies showed that conventional p-y curves are not suitable in designing the foundation. More advanced methods, such as the finite element method, are necessary to model the offshore wind turbine foundation. In addition, these studies focused on the analysis of the foundation itself, so the effect on the structural response of the tower merits further research. The present study aimed to compare different foundation modeling approaches, focusing on their effects on the structural response of the wind turbine tower. We integrated wind turbine aerodynamic simulation with different models of the foundation. We confirmed that ignoring the flexibility of the foundation caused significant error in wind turbine tower behavior. Between the p-y curve-based model and finite element-based model, the change in maximum moment was insignificant, but the maximum tilt angle increased over 14% in the finite element model. Therefore, the finite element approach is recommended to obtain a conservative design when large tilt angles may cause serviceability issues.