Heat transfer analysis of rectangular concrete-filled steel sections

This research presents a detailed parametric study of the thermal behaviour of concrete-filled steel tubular (CFST) sections as they respond to different fire exposure conditions. After validation of the model, 18 finite element models were developed to analyse the effects of fire duration, section size, steel tube thickness, aspect ratio, and heating configurations on heat transfer behaviour. The temperature-dependent thermal properties per Eurocode standards were employed to model material degradation. The results indicate the effects of geometric parameters and heating orientation on the distribution of internal temperatures and temperature gradients. While the concrete core delays heat progression, it was found from this study that cross-sectional area and fire exposure direction significantly dictate the rise of core temperature and heat flux (HFL). Moreover, the analysis investigates the insight progression of thermal interaction at the steel–concrete interface, mainly in square CFSTs - an area with fewer detailed investigations. These findings offer improved thermal characterisation of CFSTs and provide an excellent base for performance-based coupled thermo-mechanical analysis to enhance fire-resistant design.