A comparative experimental study between stiffened and unstiffened stainless steel hollow tubular stub columns

This paper presents a comparative experimental study between stiffened and unstiffened stainless steel hollow tubular stub columns using the austenitic stainless steel grade EN 1.4301 (304). Stainless steel structural shapes are becoming increasingly complex as cold-forming techniques are advancing. The unstiffened stainless steel tubular stub sections were fabricated by welding four angles or two channels tip-to-tip, whereas the stiffened sections were fabricated by welding four lipped angles or two lipped channels at the lips. Therefore, the stiffeners were formed at the mid-depth of the sections. In total, five columns without stiffeners and five columns with stiffeners were tested. Series of tests were performed to investigate the effects of cross-section shape on the behaviour and strength of stainless steel tubular stub columns. The measured average overall depth-to-width ratios (aspect ratio) varied from 1.0 to 1.8. The depth-to-plate thickness ratio of the tube sections varied from 60 to 90. Different lengths of columns were selected to fix the length-to-depth ratio to a constant value of 3. The specimens were subjected to uniform axial compression. The column strengths, load–axial strain relationships and failure modes of the columns are presented. The column strengths obtained from the experimental study were compared with the design strengths calculated using the European Code for cold-formed stainless steel structures and the ASCE Standard. The results of the experimental study showed that the design rules specified in European specifications and ASCE standard generally overestimate the column strengths of stainless steel square and rectangular hollow section stub columns fabricated by cold-forming and welding.