Dynamic response of offshore wind turbine monopile foundation under wind-wave loads

Physical experiments provide the best representation of foundation behaviour in any environmental conditions offshore; however, they are very costly, especially since the on-site conditions vary. Hence, it is not a cost-effective approach. In contrast, numerical modelling is relatively cheaper, but requires long computation time and a high level of expertise to perform a successful numerical calculation. The main objective of this paper is to develop a simple and fast response analysis that requires less computational time and expertise. First, an analytical model is developed to study the dynamic behaviour of the pile by extending the beam on an elastic foundation. Second, the analytical results are verified by using the finite-element software, Abaqus. Finally, a parametric study is carried out with the established numerical calculation model to investigate the modal shapes of the pile model, limit states of the offshore wind turbine (OWT) and pile capacity for different loading conditions and aspect ratios. The proposed analytical model demonstrates a degree of error less than 10%, indicating great reliability and the potential for practical application. The parametric results indicate that the OWT is more likely to fail by yielding than buckling and the soil resistance at the pile periphery is highly affected by the aspect ratio.