Ultimate strength of ship hulls under torsion

For a ship hull with large deck openings such as container vessels and some large bulk carriers, the analysis of warping stresses and hatch opening de formations is an essential part of ship structural analyses. It is thus of importance to better understand the ultimate torsional strength characteris tics of ships with large hatch openings, The primary aim of the present stu dy is to investigate the ultimate strength characteristics of ship hulls wi th large hatch openings under torsion. Axial (warping) as well as shear str esses are normally developed for thin-walled beams with open cross sections subjected to torsion. A procedure for calculating these stresses is briefl y described. As an illustrative example, the distribution and magnitude of warping and shear stresses for a typical container vessel hull cross sectio n under unit torsion is calculated by the procedure. By theoretical and num erical analyses, it is shown that the influence of torsion induced warping stresses on the ultimate hull girder bending strength is small for ductile hull materials while torsion induced shear stresses will of course reduce t he ship hull ultimate bending moment. (C) 2001 Published by Elsevier Scienc e Ltd.