Elastic flexural local buckling of Litzka castellated beams: Explicit equations and FE parametric study

摘要

This work presents the development of explicit equations for the prediction of elastic local buckling critical stress of castellated beams subjected to pure bending, considering the interaction between flange and web. Eigenvalue analyses are carried out for Litzka-type beams using Finite Element Method (FEM) to gather information on the buckling modes and critical stresses for combinations of usual flange-to-web width and thickness ratios. The representative compression 'tee' is analyzed using the Generalized Beam Theory (GBT) to study the influence of stress gradient and member length in the critical stress. The influences of flange torsional stiffness and web transverse bending in the 'tee' behavior are studied and an energy method is adopted to derive the prediction equations. It is shown that the proposed approach leads to a good agreement with the FEM results, with an average difference of 0.955 +/- 0.063, whereas current guidelines may significantly over or underestimate actual critical stresses for low flange-to-web width ratios. It is finally shown that this buckling mode may become relevant for castellated beams using high-strength steel.