Stub column behaviour of heat-treated and galvanized RHS manufactured by different methods

A complementary study showed that hot-dip galvanizing can sometimes significantly change the residual stress properties of cold-formed rectangular hollow sections (RHS). Hot dipping the RHS specimens in a molten zinc bath maintained at 450 degrees C for 10 min provided a partial residual stress relief comparable to the onerous heat treatment specified in ASTM A1085 and CSA G4020/G40.21. Hence, further research is needed to: (1) quantify the effects of galvanizing, and (2) determine the optimized heat treatment duration for a partial residual stress relief for improvement of column behaviour. In this study, the effects of galvanizing and heat treatments to different degrees on the stub column behaviour of cold-formed RHS has been investigated comprehensively for the first time, by means of 36 stub column tests. The RHS specimens were manufactured by two dominant cold-forming methods: (1) indirect-forming from circular to rectangular, and (2) direct-forming. The nominal yield stresses of the materials ranged from 350 to 690 MPa. The RHS stub column test matrix has 10 different width-to-thickness ratios and includes both nonslender and slender sections. (C) 2019 Elsevier Ltd. All rights reserved.