Buckling analysis of cold-formed steel channel-section beams at elevated temperatures

• Fire performance of plasterboard protected CFS channel beams is investigated through heat transfer, pre-buckling and buckling analyses.
• Significant temperature variation is found within the cross-section.
• The pre-buckling stress distribution is remarkably affected by the temperature distribution.
• Apparent difference in buckling behaviour is found between varying and constant temperatures.
• The temperature variation within the section has a significant influence on the slenderness of CFS beams.

This paper presents a numerical investigation on the buckling behaviour of plasterboard protected CFS channel-section beams subjected to uniformly distributed loads when exposed to fire on its one side. The work involves three phases, namely heat transfer analysis, pre-buckling analysis and buckling analysis. The heat transfer analysis is accomplished using two-dimensional finite element analysis methods, from which the temperature fields of the channel-section beams are obtained. The pre-buckling analysis is completed using the Bernoulli bending theory of beams with considering the effects of temperature on strain and mechanical properties. The buckling analysis is performed using combined finite strip analysis and classical Fourier series solutions, in which the mechanical properties are considered to be temperature dependent. The results show that there are significant temperature variations in web, fire exposed flange and lip. Also, it is found that the buckling behaviour of the beam with temperature variation in its section is quite different from that of the beam with a constant uniform temperature in its section.