Random design variables and sensitivity factors applicable to ship structures considering combined bending moments

Abstract

Sensitivity analysis enables the designers to determine the most important random variable responsible for the failure of ship structures. Vertical bending is the most important to assess the strength of a ship, but horizontal bending moment also plays a pivotal role in the safety assessment of ship structures. The method for the reliability analysis taking account of the combined bending moment is presented. The interaction equation between the vertical and horizontal bending moments has been derived using Smith's method, and the limit state function for the reliability analysis has been modelled from the interaction equation. The wave loads are calculated using an International Association of Classification Societies (IACS) rule. The study shows the importance of the contribution of the design variables towards the uncertainty of the limit state function and the advantages for using the sensitivity factors for safety assessment of ship structures.