Simplified Method to Predict the Temperature Distribution in Normal- And High-Strength Concrete Circular Cross Sections Exposed to Fire

This paper presents a formula for evaluating the temperature distribution in RC circular columns exposed to standard fire scenarios. Unlike the detailed solution to the heat transfer differential equation, the proposed model is simple to use. Application of the proposed formula does not require numerical analysis, and it can be applied to generate, with sufficient accuracy, temperature distributions within a cross section at any specified time and location. Derivation of the formula was based on a regression analysis of a large set of results generated by finite difference calculations. The regression formulas yielded a root-mean-square error of 21.7°C, where most errors within the practical temperature range of 200°C-800°C do not exceed ±15% (compared with the numerical results). The proposed model was verified against the results of the finite difference calculations and validated against published experimental results. It can provide predictions for both normal- and high-strength concrete, with different aggregate types and different moisture contents. The simplification and the wide applicability of the proposed model make it worthwhile and useful for structural fire design, as illustrated by the examples given at the end of the paper.