A Simplified Progressive Collapse Analysis of Ultimate Longitudinal Strength of Ship Structures

A simplified procedure is developed for predicting the ultimate strength of hull girder based on the basic progressive collapse method.The normalized stress-strain relationship of structural element is introduced by applying beam-column theory,elastoplastic assumption,and plastic joint theory.The total bending moment is obtained by integrating the contribution of all elements,and the ultimate bending moment is defined by the moment corresponding to the point with zero or negative slope in the moment-curvature relationship.The complete procedure has been coded into a FORTRAN program and tested against four ship/box girder sections. The results obtained from the present program appear to be quite satisfactory.It shows the advantage of present method to predict the ultimate strength of hull girder in ship design.