Evaluation of Lateral Response in Offshore Wind Monopiles: A Comparison of Analytical and Numerical Approaches

This paper investigates results of analytical and numerical approaches for analyzing static response of monopile foundations in a comparative way. In this study, static behaviour of NREL 5 MW wind turbine foundation under lateral loads was analyzed using the Winkler Approach with linear and nonlinear springs individually and numerical modelling using finite element method. The linear Winkler method, while straightforward to use, considerably underestimates both the initial stiffness and the ultimate resistance whereas utilizing the nonlinear Winkler springs, reflect the expected bilinear behaviour characterized by a rigid initial reaction and a limit in ultimate capacity. It was observed that three-dimensional numerical modelling provides a conservative assessment of soil resistance, owing to comprehensive stress-strain soil modelling and realistic boundary effects, which show a more gradual mobilization of resistance.