Buckling of axially loaded castellated steel columns

The majority of the existing literature on castellated members is focused on beams and very little work has been done on the buckling stability of castellated columns, although castellated members have been used as columns in tall buildings to sustain axial loads. This paper presents a new analytical solution for calculating the critical buckling load of simply supported castellated columns when they buckle about the major axis. This analytical solution takes into account the influence of web shear deformations on the buckling of castellated columns and is derived using the stationary principle of potential energy. The formula derived for calculating the critical load is validated for a wide range of section dimensions using the data obtained from finite element analyses published by others. It is found that the influence of web shear deformations on the critical buckling loads of castellated columns increases with the cross-sectional area of a tee section and the depth of web opening, but decreases with the length and the web thickness of the column. It is shown that the inclusion of web shear deformations significantly reduces the buckling resistance of castellated columns. Neglecting the web shear deformations could cause an overestimate of the critical buckling load by up to 25%, even if a reduced second moment of area is used. The analytical solution agrees well with the finite element solutions.