Sub-Zero Temperature Behaviour of Cold-formed steel Members

Abstract

Cold-formed steel (CFS) industry has opportunities to expand the use of CFS in sub-zero temperature environments, such as Arctic and Antarctic regions, large scale refrigeration facilities and off-shore structures. Although the behaviour of hot-rolled steel members in such environments has been investigated, limited studies are available for CFS members at sub-zero temperatures. Thus, tensile tests were conducted on low and high strength cold-rolled steel sheets to determine their mechanical properties in the temperature range of 20 to -70 ℃. Predictive equations were developed to determine the sub-zero temperature mechanical properties of CFS using their ambient temperature mechanical properties. Sub-zero temperature ductility of CFS was investigated against CFS design standards. Also, the issues of performing standard toughness tests on CFS due to dimensional limitations were identified. Moreover, CFS stub columns were tested at sub-zero temperatures to investigate their behaviour. Tests showed that there were no premature failures caused by brittle fracture, even after significant localised deformations during the post-ultimate phase. In all cases, the ultimate capacity increased considerably even at temperatures below -50 ℃, especially for low strength steel columns.