Advanced closed-form ultimate strength formulation for ships

The aim of this paper is to develop an advanced ultimate strength formulati on for ship hulls under vertical bending moment. Since the overall failure of a ship hull is normally governed by buckling and plastic collapse of the deck, bottom, and sometimes the side shell stiffened panels, it is of cruc ial importance to accurately calculate the ultimate strength of stiffened p anels in deck, bottom and side shell for more advanced ultimate strength an alyses. In this regard, the developed formulation is designed to be more so phisticated than previous simplified theoretical methods for calculating th e ultimate strength of stiffened panels under combined axial load, in-plane bending and lateral pressure. Fabrication-related initial imperfections (i nitial deflections and residual stresses) and potential structural damage r elated to corrosion, collision, or grounding are included in the panel ulti mate strength calculations as parameters of influence. All possible collaps e modes involved in collapse of stiffened panels, including overall bucklin g collapse, column or beam-column type collapse (plate or stiffener induced collapse), tripping of stiffeners and local buckling of stiffener web, are considered. As illustrative examples, the paper investigates and discusses the sensitivity of parameters such as lateral pressure, fabrication-relate d initial imperfections, corrosion, collision and grounding damage on the u ltimate strength of a typical Cape size bulk carrier hull under vertical be nding.