## 3 Fire Test Results and Discussion
\begin{array}{ll}c_{\text{c}}=900&20\ ^{\circ}\text{C}\leq T\leq 100\ ^{\circ}\text{C}\\ c_{\text{c}}=900+(T-100)&100\ ^{\circ}\text{C}<T\leq 200\ ^{\circ}\text{C}\\ c_{\text{c}}=1000+(T-200)/2&200\ ^{\circ}\text{C}<T\leq 400\ ^{\circ}\text{C}\\ c_{\text{c}}=1100&400\ ^{\circ}\text{C}<T\leq 1200\ ^{\circ}\text{C}\\ \end{array} \right. \tag{2}\]  
\[\left\{ \begin{array}{ll}\lambda_{\text{c}}=\alpha\lambda_{\text{cu}}+(1- \alpha)\lambda_{\text{cl}},\ \alpha\in[0,1]\\ \lambda_{\text{cu}}=2-0.2451(T/100)+0.0107(T/100)^{2}\ 20\ ^{\circ}\text{C}\leq T\leq 1200\ ^{\circ}\text{C}\\ \lambda_{\text{cl}}=1.36-0.136(T/100)+0.057(T/100)^{2}\ 20\ ^{\circ}\text{C}\leq T\leq 1200\ ^{\circ}\text{C}\\ \end{array} \right. \tag{3}\]  
Figure 11 compares the calculated and measured temperature-time curves at Section 2-2 of Specimen S120C. In general, the calculated results agree well with the measured results, so the numerical method provides a good prediction of the temperatures at any point on Section 2-2. Figure 8: Cracks of specimen. (**a**) Cracks on the soft; (**b**) cracks on the front and back surfaces. Figure 9: Meshes on Section 2-2. Figure 12 compares the measured temperatures at Section 1-1 with the calculated temperatures at Section 2-2 for the different specimens. The following can be observed:  
(1) The temperatures at both Section 1-1 and Section 2-2 rapidly declined with distance from the heated surface in all of the specimens. (2) For a heating time of 60 min, in Specimens S60, S120, and S120C, the temperature at Section 1-1 declined more sharply than that at Section 2-2 for the first 25-60 mm from the heated surface. Between 60 and 270 mm, however, the temperature at Section 1-1 declined more gradually than that at Section 2-2. In addition, the temperature at most of Section 1-1 was below 100 \({}^{\circ}\)C and lower than that at Section 2-2. This is probably because water vapor released from the concrete accumulated in the narrow joint gap and barely dissipated. That would have hindered heat transfer into the joint gap to  
Figure 11: Comparison of calculated and recorded temperature-time curves related to Section 2-2 of Specim S120C. Figure 12: Comparison between measured temperatures at Section 1-1 and calculated temperatures at Section 2-2. (**a**) Heating time = 60 min; (**b**) heating time = 120 min. Figure 10: Specific heat of concrete as a function of temperature with different moisture contents. some extent. Please note that the initial joint opening (see Table 1) of S60C was larger than those of the other specimens. Consequently, for Specimen S60C, the temperature at Section 1-1 was higher than that at Section 2-2 for a heating time of 60 min. The larger initial joint opening promoted heat transfer into the joint gap and led to higher temperatures in the gap than in the neighboring concrete. (3) For a heating time of 120 min, the temperature at Section 1-1 was higher than that at Section 2-2. This is because all of the moisture within the joint gap eventually dissipated with the longer heating time. Heat then penetrated the gap, increasing its temperature. [PERSON] [4] observed a similar phenomenon in fire tests with reduced-scale segment joints. In his study, the surface temperature of the concrete near the joint was higher than that farther away. This is mainly due to heat being transferred into the joint gap, the nearby concrete was heated on two sides. Note, though, that this is different to what was observed by [PERSON] and his co-workers [5]. They observed that the temperature in the crack was lower than that of the neighboring concrete. This is presumably because the joint opening tested here (9.5-11.8 mm) was much larger than the crack width in [PERSON]'s tests (0.5-3 mm). Figure 13 presents temperature-time curves for the joint bolts. The temperatures of the bolt ends were much higher than those in the mid-point during the entire heating process.