Offshore wind jacket foundation design challenges in earthquake regions

Emerging offshore wind markets in the East Asian region demand seismic design for offshore wind support structures. This paper analyses site conditions and design methods applicable for jacket designs in earthquake regions. Required seismic standards, guidelines and load cases are described in detail. A design case study identifies the relevance of seismic impact in the design of jacket support structures for offshore wind turbines. In a design case study, jacket structures for a typical North Sea site and East Asian conditions were developed based on a generic 12.5 MW wind turbine. For different methods during the design process (conceptual and detailed design), the resulting ultimate limit state loads at the top and bottom of the jacket are compared. Summarising the case study, the governing design situations are identified, and recommendations for seismic design practice are derived.