Post-fire flexural and web-crippling behaviour of cold-formed steel built-up section beams

Abstract

Worldwide, industrial constructions are frequently built using light gauge materials like Cold-Formed Steel (CFS) sections due to its lightweight and affordable design systems. One important aspect of building design and construction that must be considered is fire safety. The research involved studying flexural and web-crippling behaviour of CFS built-up beams subjected to controlled high-temperature conditions, then it was cooled to room temperature by furnace cooling method. Ten back-to-back built-up CFS sections were prepared to check structural performance after exposure to elevated temperatures of 500°C, 600°C and 700°C in an electrical furnace. The Finite Element (FE) modelling results are validated by experimental results. The validated FE models were then employed to carry out a comprehensive parametric study to investigate the effects of different web-to-thickness ratios, as well as sectional size to thickness ratio. The results demonstrated that the load carrying capacity and bending moment for flexural behaviour and web-bearing capacity for web-crippling behaviour of the CFS members can be significantly affected, (up to 56.04% and 37.26%, respectively with reference temperature) after exposure to elevated temperature. From the study, it is concluded optimizing the web height to thickness ratio is crucial for enhancing the structural performance of CFS components. However, higher temperatures resulted in a greater reduction in the load carrying capacity of the specimens.