With increasing power classes of offshore wind turbines, more and more influence factors in different life phases of jacket substructures should be considered to improve the feasibility, economic efficiency and approvability in the jacket design process. The conventional design methods of jacket substructures for offshore wind turbines are complex and expensive. In this case, more efficient design methods should be raised and investigated. The current work in this paper contributes to the development of a database of windfarms with jacket substructures, in order to consider sufficient influence factors during the life process of the structure into the structural design. The correlations between pairs of design parameters (feature pairs) in the database are investigated. According to the results of statistical analyses, a data-based method to simplify the conceptual design of offshore jacket substructures is developed, which is intended to provide a preliminary jacket topology to the further design phases.
In comparison with building structures, the substructures of offshore wind turbines are unifunctional structures whose main task is to transfer loads (Van Der Tempel, 2006). The structural design of offshore substructures is generally based on explicit theoretical and practical calculation methods as well as on the engineer's intuition (Li et al., 2021), which is the ability to make statements about a structure based on individual experience and unconscious perception. Regarding the first part, the calculation methods for offshore substructures have been developed over the past decades. The conventional methods are based on three design phases, i.e. conceptual design, iterative design and detailed design with the structural assessments in ultimate limit states (ULS), fatigue limit states (FLS) and accidental limit states (ALS) for specific design load cases (BSH, 2007; Van Der Tempel, 2006; Veritas, 2014). With these calculation methods, a number of researchers have investigated the structural behaviors of offshore substructures in specific load cases (Chew et al., 2016; Chen et al., 2016; Damiani et al., 2016). With higher requirements to the rated power of offshore wind turbines, the development of offshore megastructures is already ongoing. In this case, boundary conditions from manufacturing to installation of the offshore substructure or special requirements from maintenance also have large impacts on feasibility, economic efficiency and approvability of offshore windfarm projects. Therefore, it is necessary to consider essential partial aspects in the life cycle into the substructure design, which are based significantly on implicit knowledge or experiences of engineers that cannot be completely described mathematically.