Strength and Fatigue Assessment of Extended Bilge Keels for FPSO/FLNG

Abstract This paper presents advanced analysis procedures for the strength and fatigue assessment of FPSO bilge keels which are developed under the joint development project (JDP) between ABS and Chevron. For enhanced performance of FPSO/FLNG units in harsh environments, large bilge keels with extended depth are often considered in real designs. Damage cases of the bilge keels have been reported, but industry guidelines on the structural design of the bilge keels are very limited due to the nonlinearity of hydrodynamic loads on the bilge keels. In this paper, a first-principles approach is proposed by introducing the Computational Fluid Dynamics (CFD) based hydrodynamic loads into the Dynamic Loading Approach (DLA) based full ship FE structural analysis for the strength and fatigue assessment of bilge keels. The design loads at a 10-8 probability level are considered for strength assessment and the long-term Weibull distributions of stress range are considered for the simplified fatigue assessment at critical locations.