Calculation of Thermal Fields of Cracked Concrete at Elevated Temperatures

Abstract

This paper analyzes the effects of cracking on the thermal field of concrete at elevated temperatures. In four concrete specimens with pre-made cracks, fire tests were performed. Then finite element analysis and theoretical analysis were conducted, which have indicated that heat conduction was the primary source of heat transfer in cracked concrete. At last mathematical software MATLAB was used to calculate the temperatures distributions of a simplified model based on theoretical analysis, which were compared with the test results. The results show that as the thermal diffusion of air is far greater than that of concrete, there is an increase in the thermal propagation through the cracked regions in comparison with undamaged regions, and the temperatures increase with the increase of cracks widths. The temperature of concrete farther away from a crack was less affected because concrete has a lower thermal diffusion coefficient. The water content of concrete has an impact on the temperature distributions, which should be considered at the early stage of fire when determining the concrete temperature distributions.