Longitudinal strength reliability of a tanker hull accidentally grounded

This paper presents a reliability analysis of a damaged Suezmax double hull tanker, using a first order reliability method. The accidental grounding being analyzed is assumed to be centered on the keel, which is the worst possible scenario from a strength degradation point of view. The ultimate strength of the damaged tanker, to be used in the formulation, is calculated by means of a specific structural code, in which the damage is simulated by the removal of the damaged elements. Different sizes of the damage are analyzed and a relationship is established with the reliability index related to the ultimate strength. The wave induced loads are calculated from long-term distributions related to the “Global Wave Statistics” database. The still-water loads are defined from the ship loading manual. A parametric study about the impact of the ultimate bending moment of the damaged ship on the reliability index is then performed.