Dynamic response analysis of a monopile-supported offshore wind turbine under the combined effect of sea ice impact and wind load

The existence of drifting ice is a key challenge for structural design of offshore wind turbines (OWTs) in cold regions. To better understand the structural behavior of OWT under combined sea ice impact and wind load effects, this paper investigates the dynamic response of a monopile-supported OWT using the nonlinear finite element method. The interaction between the OWT and ice impact, wind loads and soil contact are addressed in the developed numerical models in LS-DYNA. The coupling between the main program and the aerodynamic damping model is achieved by a user-defined load subroutine. To calibrate and verify the ice material model and the simulation technique, model test data are used of ice impacts with a nearly vertical monopile foundation. In the case study, numerical simulations of the interaction between a typical 5-MW monopile-supported OWT and an ice sheet are performed under various combined load scenarios. The dynamic response characteristics are presented and the effects of ice drifting speed and mean wind speed are elucidated by statistical methods. Finally, insights into the ice loads are obtained by comparing the simulation results against two international design standards. The present study contributes to an improved understanding of load effects of monopile OWTs in cold regions.