Major-axis elastic buckling of axially loaded castellated steel columns

Perforated-web steel sections have been used as structural members since the Second World War in an attempt to enhance the flexural behavior without increasing the cost of the material. Nowadays, such sections are widely used in a variety of geometries suitable for various loading conditions. In the current study, the finite element method is used to investigate the major-axis buckling characteristics and associated buckling capacity of axially loaded I-shaped steel columns. Extensive numerical analyses are conducted to evaluate the reduction in buckling capacity of castellated columns due to shear and flexural deformations. Obtained results are used to identify a dimensionless buckling modification factor, η, and the associated equivalent section properties that can be implemented to assess the critical buckling load of the considered columns. The study considers a wide range of practical geometric dimensions, as well as, various columns’ end conditions. A simplified procedure is suggested to evaluate the buckling capacity of castellated columns. Charts are developed to enable practitioners to readily estimate the buckling load of such a type of castellated columns more accurately.