Posters

Abstract

Offshore wind floating foundations cost is mainly driven by 1) Steel quantities and grades, and 2) Ease of fabrication. In typical oceanic conditions, their design is generally fatigue driven. As a main driver, the fatigue validation of the design needs to be dealt with during all project phases, starting as early as possible to secure a robust and reliable design that, in turn, guarantees the bankability of commercial farms projects. Ease of fabrication for steel structures comes down to 1) the use of standard sub elements readily available on the market (for example plates or profiles dimensions and thicknesses), 2) to the minimization of weld quantities and weld complexity, and 3) the compatibility of the design with a wide range of worldwide available fabrication lines, allowing for maximizing mechanized fabrication. Typical floating wind concepts focus on design at early stages, based on hydrodynamic performance and structural behavior in extreme conditions. This is common practice as fully coupled time domain fatigue evaluation is extremely computationally intensive when performed with standard methodologies and tools. Furthermore, fabrication methodology is usually addressed during project execution in coordination with the fabrication contractor, and not at initial design stages. This typical process leads to 1) potential significant design changes and structural reinforcements due to fatigue loads within project execution, 2) potential significant design changes to optimize fabrication scheme during project, or 3) a sub-optimal fabrication scheme leading to increased fabrication duration and cost. Hence, we will present the methods developed to guarantee an optimal design and cost for a given floater design within early project phases. The presentation will discuss the methodologies developed, their interest, and main results. The application case of this method will consider STAR1 semi-submersible floating foundation.