Influence of model parameters on the design of large diameter monopiles for multi-megawatt offshore wind turbines at 50-m water depths

Relevant modelling approaches towards the design of a large diameter monopile for 10 MW offshore wind turbines at 50-m water depths are considered to evaluate their respective impacts on the structural integrity. The analysed models or model parameters include soil-structure interaction, construction errors, and damping. The study is conducted on a reference structure verified with respect to fatigue, ultimate (strength, stability, and soil capacity), and serviceability limit states after fully coupled load simulations. Models and their parameters are carefully obtained in line with the case in hand. Perturbation analysis is used to assess the impact of the soil model, the geometric imperfections, and the damping on the structure safety and robustness. Results show that all of them significantly influence the fatigue lifetime, the geometric imperfections and the soil model impact the ultimate stresses, and the soil model affects the deformations of the final design, from which guidance on the optimal selection of these parameters leading to material savings is made.