Thermal Properties and Heat Transfer in Concrete Filled Steel Tube Reinforced Concrete Columns Exposed to Fire

The thermal properties of concrete and steel were concerned. Specific heat, thermal conductivity, density and thermal contact conductance at the steel-concrete interface were compared from different researchers. Different ways of calculation method of heat transfer were summarized. A finite element method (FEM) procedure was suggested to calculate temperature distribution of concrete filled steel tube reinforced concrete (CFSTRC) column with suitable thermal properties of concrete and steel. The results showed that different models of thermal properties of concrete and steel dispersed widely. The dispersion of thermal properties of steel was smaller than that of concrete. Moisture and aggregate type had some influence on specific heat of concrete, and aggregate type had some influence on thermal conductivity of concrete. Thermal conductivity of reinforcing steel and stainless steel showed a reverse trend with temperature increasing. The influence of temperature on density of concrete and steel was slightly. Cross-sectional type had some influence on thermal contact conductance at the steel-concrete interface in some models, but constant values have been used extensively by different researchers. According to experimental validation, the FEM procedure was capable of predicting temperature distribution of CFSTRC columns with an accuracy that was sufficient for design purposes.