Maximum temperature prediction for concrete sections during cooling phase

Abstract

Maximum temperatures at each location within a concrete cross section exposed to fire during both heating and cooling phases are required to evaluate residual strength of RC members. Available methods for predicting the maximum temperature have been limited to complicated numerical methods. Therefore, this study proposed a simplified equation to predict the maximum temperature by using a parametric study based on a validated finite element (FE) model. One dimensional heat transfer analysis under a standard fire curve was a scope of this study. Investigated parameters were section thicknesses, fire durations and cooling durations. Based on the parametric study and an energy based method, simplified equations to evaluate the maximum temperature during the cooling duration of 4 h were proposed. The equations were formulated as functions of an effective thickness, a temperature at the non-fire exposed surface and an exponent of temperature profiles at the end of the heating phase. Comparing with those of the FE results, the predicted maximum temperatures agree well and have the coefficient of determination of 0.9737.