ABSTRACT
In the last decades, there has been a focus in International Association of Classification Societies (IACS) to improve and harmonize the buckling methods and a dedicated maintenance group has continuously been working with maintenance to identify critical issues. The most recent developments have been carried out by a project team established in 2018, and this paper presents some of the improvements for the buckling formulations for stiffener buckling and the background theory. Generally, some new buckling formulae are proposed focusing on the global elastic buckling mode for stiffened panels subject to combined loads (biaxial loads, in-plane shear force and lateral pressure), the torsional buckling mode for high-web stiffeners, and also improvements of buckling formulae specific to plate panels fitted with sniped stiffeners. Regarding each of these items, the theoretical background is presented and numerical calculations of typical panels from bulk carriers and oil tankers are carried out, including some identified special panels for which the previous buckling formula might give inaccurate results. Comparison with extensive linear and nonlinear FE analyses verifies the increased accuracy of the new buckling formulae and demonstrates the effectiveness of corresponding rule improvements which have been included in latest Common Structural Rules (CSR).
