Heating Mechanism of Double Tubular Steel Columns Part 2 Numerical Analysis and Comparison with the Experimental Results

As shown in Figure 1, the initial condition of the method was that the heating temperature T0 (fire room) was 20°C and the temperatures of the gaps inside the steel tubes (T3 and T6 ) were 20°C. The coefficients of heat transfer H1 , H2 , H3 , H4 and H5 (W/m2K) were given as follows. Here, H1 , H2 , H3 and H4 were the coefficients of heat transfer for the external surface of the outside steel tube, the internal surface of the outside steel tube, the external surface of the inside steel tube and the internal surface of the inside steel tube respectively. And H5 was the coefficients of radiative heat transfer between the internal surface of the outside steel tube and the external surface of the internal surface of the inside steel tube.