Testing and design analysis of WAAM high strength steel square hollow sections in compression

Wire arc additive manufacturing offers significant potential for structural engineering applications through its ability to produce complex metallic components with geometric freedom and cost-effectiveness. This paper examines the geometric characteristics and local buckling behaviour of wire arc additively manufactured (WAAM) ER110S square hollow section (SHS) stub columns. The geometric features and initial local geometric imperfections of the specimens were characterised by means of 3D laser scanning and further data analysis. Eight fixed-ended stub column tests were conducted; material yielding was achieved in stocky specimens, whereas local buckling occurred before the yield stress was reached in slender specimens, and the location of local buckling was consistently found to correspond to that of the largest initial local geometric imperfection. The obtained test data were used to assess the design provisions in European, American and Australian standards. The results demonstrate that current Class 3 or slenderness limits are unsafe for internal plate elements of SHS under compression, and that all three examined specifications provide overestimated unfactored ultimate load predictions for relatively slender SHS. The findings highlight the necessity of revised slenderness limits and ultimate load formulations, based on the experimental data, for WAAM high strength steel SHS stub columns.