Structural Design of a Prestressed-Concrete Spar-type floater for 10 MW wind turbines

Abstract

Prestressed concrete is gaining growing interests as an alternative to steels for the construction material for floating platforms of wind turbines due to its low material costs. Investigation of the characteristics of the concrete structure under the fluctuating loadings are necessary to ensure the structural integrity, where a reference model of both the floating concrete platform and accompanying structural design are highly useful. In this study, a reference model for prestressed-concrete spar-type floater for 10 MW wind turbines is designed together with its concrete structure. Frequency-domain analysis showed that an optimum floater diameter that gives minimum pitch angle could be found. Although the maximum pitch angles were similar for floaters with diameters of 15 m to 17 m, structural design showed that the case with the wall thickness of 0.35 m will subject to prestressed-concrete steel yielding, concrete bending cracks, and shell buckling due to water pressure. Finally the reference model is designed for a floater diameter of 16 m and wall thickness of 0.45 m.