Numerical modeling of temperature distribution in square reinforced concrete cross-sections heated on four sides under fire conditions along with determination of the location of the 500C isotherm and reinforcement temperature

In the article, a series of simulations of unsteady heat flow in reinforced concrete elements heated from four sides were conducted. Selected square cross-sections with side lengths ranging from 16 to 40 cm were examined. Heating of the elements was assumed according to the standard fire curve over a period from 0 to 240 minutes. The study investigated the temperature of the cross-section at distances of a = 2, 4, 6, 8 cm from the heated Surface of the cross-section and determined the location of the 500C isotherm in fire scenarios R30–R240. Additionally, nomograms were developed that may be useful for designing reinforced concrete columns or beams under fire conditions using the 500C isotherm method