Effect of uncertain factors on the hull girder ultimate vertical bending moment of bulk carriers

Abstract

This paper focuses on the effect of initial imperfections and corrosion wastage on the age related strength degradation of bulk carriers. At the beginning, the initial imperfections including initial distortions and residual stresses, are employed to assess the ultimate bending moment reduction. Then, the effect of thickness degradation due to corrosion wastage on the ultimate hull girder strength is investigated. Finally, the combination of initial imperfections and corrosion wastage is considered to evaluate the residual hull girder strength. To do that, the initial imperfections of the unperfected structures and a corrosion rate estimation model for bulk carriers are introduced. A simplified method is also proposed to determine the ultimate vertical bending moment of ship hull girder subjected to initial imperfections and corrosion wastage. Additionally, the design and construction considerations for bulk carriers are made.