Influence of heating cooling regime on the buckling capacity of galvanized iron-based cold-formed steel columns with welded connections

Abstract This study provides valuable insights into the axial resistance of two different configurations and identifies different failure modes in specimens subjected to various temperatures and cooling methods. Fire exposure tests were conducted on galvanized iron (GI) based CFS columns with different configurations: back-to-back (B.B) and toe-toe (T.T) channel sections to explore the residual buckling capacity of CFS columns. Both section types, B.B and T.T channels, were assessed for axial resistance and yield deformation at elevated temperatures. In addition, two B.B sections were insulated with fire protective coatings such as perlite and zinc and heated to assess their performance. A series of finite element models were developed using ABAQUS to simulate the behavior of the tested columns under different fire exposures. Further, the results indicate that the B.B configuration exhibited a higher load carrying capacity than the T.T configuration. Among unheated specimens, B.B section has a load of 257.6kN, which is 21.61% higher than the load obtained for T.T section, which is 201.9kN. Among the coated specimens, the section coated with perlite has a load of 250.2kN after heating for 60 min, which is virtually unchanged from the unheated specimen. The difference between coated and reference is just 2.87%. The section that was coated with zinc had a load of 225.6kN, which is 9.83% lower than the other coated specimen. In all instances, the B.B configuration sections demonstrated higher axial stiffness than the T.T configuration sections. This trend persists throughout the study, with axial stiffness decreasing as the duration of heating increases.