Modelling Approaches for Thermal Response of RCB Under Fire Exposure

Manco Rivera M.R.; Carbajal M.C.; Guarniz Avalos G.O. · International Journal of Engineering Trends and Technology (2025) · DOI: 10.14445/22315381/ijett-v73i12p101

Resumen

Reinforced Concrete Beams-RCB are widely used in buildings, bridges, and other types of infrastructure due to their versatility and high load capacity. Besides the typical service conditions, such structural systems can experience unexpected events, such as partial or total fires. Experimental tests are so expensive, and there is little data regarding these accidents. The current regulation offers some analysis options for this type of phenomenon. A localized fire generates a highly nonlinear temperature gradient that, in some cases, is capable of generating stresses in RCB structures of the same order of magnitude as their dead and live loads. These stresses are due to restrictions on thermal expansion (or contraction) and can give rise to cracking that reduces or even eliminates these stresses. Computational Fluid Dynamics (CFD) techniques provide a highly detailed description of fire-induced thermal phenomena, but their practical implementation remains limited due to computational constraints. This research proposes an integrated strategy that couples CFD-based fire analysis with Finite Element (FE) heat transfer modelling to estimate the thermal response of RCB under localized fire conditions. Additionally, this thermal field is compared with that obtained with the LF-ESF model. The analysis is performed with a unidirectional coupled model in which data derived from the CFD simulation are subsequently incorporated into the Finite Element model to determine the thermal behaviour of the system. The LF-ESF model employs updates to classical models for the temperature field distribution and heat transfer coefficients. It also employs an ellipsoidal solid flame model to describe radiative heat transfer. The results obtained are satisfactory, showing that the LF-ESF model presents conservative results, while the CFD-FEM models obtain more precise temperatures in the RCB but at a considerably higher computational cost.

Instituciones: Universidad Tecnológica del Perú; Universidad Tecnológica de los Andes