Research on Smith’s Method of Hull Girder Ultimate Strength Based on Elastic Shakedown Limit State

Objectives In the actual navigation process, ships are subjected to cyclic bending moments caused by waves. In order to accurately assess the ultimate strength of hull structures, this study considers the elastic buckling characteristics of ship hull plating under cyclic loading. Methods As the basic structural unit of hull girders, hull stiffened plate is taken as the starting point in this study. Based on the results of nonlinear finite element numerical simulations, the average stress-average strain relationship of the stiffened plate element in Rahman's Beam-Column Method is corrected, taking into account the elastic shakedown limit state, stiffened plate types, and failure modes. Results A correction method applicable to the average stress-average strain relationship of hull stiffened plates under elastic shakedown limit state is proposed, and a Smith’s method for hull girders, based on the elastic shakedown limit state, is developed. Conclusions By comparing and analyzing the results with those from nonlinear finite element numerical simulations, it is confirmed that this method can effectively assess the ultimate strength of ship hull girders under elastic shakedown limit state.