Assessing the ultimate strength of hull girders under local and external

Ultimate bearing capacity is an important aspect of ultimate strength assessment.In order to rationally predict the ultimate bending moment of a hull girder,an integrated framework for ultimate strength assessment using the nonlinear finite element analysis method was established by taking account of the external loads.The method was combined with material nonlinearity,initial imperfection treatment and external load effects.The ultimate limit state assessment of a steel stiffened-plate structure subjected to combined biaxial compression and lateral pressure showed results that compared well with values in the literature.An oil tanker was then analyzed to demonstrate computation of a ship's ultimate bearing capacity under local loads such as water pressure and cargo pressure,and external loads such as horizontal bending and torsion.Calculations indicated that the effects of loads cannot be neglected.The ultimate bearing capacity of a hull girder not only relates to the internal structure of the ship's hull,but also the external loads.Therefore,the authors recommend that ultimate bearing capacity of individual hull girders be calculated separately,and under different load conditions.