Cyclic loading of OWT foundations: current practice and state-of-the-art

Offshore wind is a rapidly expanding, global industry which will play a critical role in global effort to decarbonise the energy supply chain. Foundations supporting offshore wind turbines are by nature subject to cyclic loading, arising through environmental (including seismic) actions and vibrations caused by operation of the turbine - and must be carefully designed for both ultimate capacity and long-term serviceability. Modelling soil-foundation interaction is an important aspect of understanding the dynamic response of the system, and for this reason cyclic design for offshore wind foundations has attracted a great deal of attention over recent years. With its origins in design practices developed for the offshore oil and gas industry, significant advances in cyclic design methods for offshore wind foundations have been made. Supported by ISSMGE Technical Committee 209 'Offshore Geotechnics', this paper reviews key topics in cyclic loading design of offshore wind turbines, with an aim to capture both the range in current practice as well as the state-of-the-art. Areas requiring further research and development are also identified and discussed.