Direct strength analysis

Direct strength analysis is a finite element assessment of a ship’s primary structure against prescribed load cases, used where the IACS Common Structural Rules require it for tankers and bulk carriers. A three-cargo-hold or full-ship model is built with shell and beam elements, loaded with the rule still-water and wave vertical bending moments, dynamic load cases, and local tank or sea pressures, then checked against yield, buckling, and (at hot spots) fatigue acceptance criteria. It supplements the prescriptive scantling formulas rather than replacing them: the rules set both a beam-theory minimum section modulus and the FE check, and the governing scantling is the larger. Mesh size and boundary conditions follow the CSR analysis procedure.