Progressive Collapse Analysis Of Ship Hulls Under Longitudinal Bending

It is very important to estimate the load carrying capacity of a ship's hull as a whole from the viewpoints of safety and economy. For this purpose, a simple method was proposed to simulate the progressive collapse behavior of a ship's hull girder subjected to longitudinal bending. In this method the cross section of hull girder is divided into small elements composed of a stififener and attached plating. For each stiffener element, the average stress-strain relationship under axial load as a beam-column in the flexural buckling mode is derived based on the approximate method, proposed by Gordo and Guedes Scares. A new equation for. predicting tripping stress of stiffeners was derived. The effects of lateral pressure and plate buckling mode are taken into account. When the tripping taking place, average stress-strain curves begin load shedding according to empirical formula.Then, a step-by-step increase of vertical curvature is applied to the hull girder assuming that the plane cross section remains plane. At each incremental step, the stress of the cross section is evaluated using the average stress-strain curves of the elements as well as the incremental bending moment due to the curvature increment.Performing sample calculations on existing girder models tests under pure bending, the rationality of the proposed method was examined. Then, the analysis was performed on existing ships, for example VLCC Energy Concentration, Bulk Carrier, Double Hull VLCC, Container Ship, then some useful conclusions were achieved.