Effect of foundation modelling on the fatigue lifetime of a monopile-based offshore wind turbine

Abstract. Several studies have emphasized the importance of modelling foundation response with representative damping and stiffness characteristics in integrated analyses of offshore wind turbines (OWTs). For the monopile foundation, the industry standard for pile analysis has shown to be inaccurate, and alternative models that simulate foundation behaviour more accurately are needed. As fatigue damage is a critical factor in the design phase, this study investigates how four different soil-foundation models affect the fatigue damage of an OWT with a monopile foundation. This study shows how both stiffness and damping properties have a noticeable effect on the fatigue damage, in particular for idling cases. At mud-line, accumulated fatigue damage varied up to 22 % depending on the foundation model used.