Influence of section profiles on flexural behavior of unsymmetrical cold formed steel sections – analytical and numerical investigation

Abstract

PurposeCold-formed steel (CFS) sections are a popular choice for constructing medium and low-rise structures that are engineered to support relatively light loads. An important characteristic of CFS sections is that they are produced without the use of heat during manufacturing. Consequently, it becomes essential to gain a comprehensive understanding in the behavior of CFS sections when exposed to fire or elevated temperatures.Design/methodology/approachIn this study, sections of 1.5 m length and 2 mm thickness were taken and analyzed to find its flexural behavior after heating them for 60 and 90 min. There were two modes of cooling phase which was considered to reach ambient temperature, i.e. air or water respectively. Performance of each sections (C, C with inclined flanges, sigma and Zed) were examined and evaluated at different conditions. Effects of different profiles and lips in the profiles on flexural behavior of CFS sections were investigated fully analytically.FindingsThe variation in stiffness among the sections with different lipped profiles was noted between 20.36 and 33.26%, for 60 min water cooling case. For the sections with unlipped profiles, it was between 23.56 and 28.60%. Influence of lip and section profile on reduction in stiffness is marginal. The average reduction in load capacity of sections for 60 min specimens cooled by water was found to be 43.42%. An increase in deflection is observed for the sections in the range of 25–37.23% for 60 min case. This is the critical temperature responsible for reduction in yield strength of material as it substantially increases the material safety margin to be considered for the design. Sections with Zed profile have shown better performance among other types, in terms of its load carrying capacity.Originality/valueThis paper deals with the flexural behavior of Galvanized (GI) based CFS unsymmetric sections at elevated temperature and cooled down to ambient temperature with air or water.