Effect of access openings on the buckling performance of square hollow section module stub columns

This paper presents a systematic finite element (FE) based parametric study to quantify the buckling capacity of perforated cold-formed and hot-rolled steel module column. The effects of various key geometric parameters such as eccentricity (location of perforation/column length), shapes (viz. circular, square and hexagonal), sizes (width/diameter) and height (depth) of perforation; and cross-sectional thickness, on the buckling performance of cold-formed and hot-rolled steel stub columns, have been investigated. Based on the analysis, the reduction in column capacity is found to be maximum when the perforation is located at column mid-height, as anticipated. The perforation shapes under consideration have been found to have marginal impact on the buckling capacity of the module stub columns, although the reduction in column capacity is seen to be in the order – square > hexagon > circular perforated columns (having same perforation size). The critical buckling capacity of perforated module column is observed to be linearly decreasing as the perforation size ratio (perforation size/flat-element width) increases. However, for the same width of perforation, increasing the perforation height up to 2.5 times the perforation width, the change in column capacity is found to be negligible. Furthermore, the applicability of existing design for perforated columns has been assessed and found that, although most of the design equations generate conservative and reliable predictions both for cold-formed and hot-rolled steel, the design formulae which are based on effective width method are found to be more accurate as compared to those which are based on total area method.