# Experimental Study on Ice Melting of Bridge Tower Crossbeams under Different Conditions
## 3 Results and Discussion
### Crossbeam Ice Melt Test  
#### 3.2.1 Influence of Ambient Temperature on Crossbeam Ice Melt  
Figure 17 shows the average temperature variation curve of the internal beam model over time, where the dashed horizontal and vertical coordinates represent the time and temperature corresponding to the start of melting ice on the beam, respectively, where the test conditions were: \(-5\,^{\circ}\)C, \(-10\,^{\circ}\)C, and \(-15\,^{\circ}\)C ambient temperature, \(0\) m/s wind speed, \(30\) mm/h rainfall, \(1\) h spraying time, \(8\) h carbon fiber hot wire energization time, and \(8\) h temperature measurement by temperature measuring instrument. The HD camera video shows that the ice column on the crossbeam started to melt at \(22\) min, \(75\) min, and \(141\) min during the tests in working condition \(5\), working condition \(6\), and working condition \(7\), respectively. The average temperature of the \(12\) temperature measurement points in the crossbeam was taken as the average temperature, and the temperatures at which the crossbeam ice started to melt were \(1.07\,^{\circ}\)C, \(1.17\,^{\circ}\)C, and \(1.2\,^{\circ}\)C, respectively.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Ambient Temperature** & **Wind Speed** & **Maximum Length** & **Minimum Length** & **Average Length of** & **Ice Thickness on the Side of the** \\
**(\({}^{\circ}\)C)** & **(m/s)** & **of Icicle** & **of Icicle** & **(cm)** & **Ice** \\ \hline \(-15\) & \(0\) & \(25\) & \(12\) & \(18.56\) & \(1\) \\ \(-15\) & \(4.5\) & \(34\) & \(20\) & \(26.34\) & \(3\) \\ \hline \hline \end{tabular}
\end{table}
Table 6: Crossbeam icicle dimensions at different wind speeds.  
Figure 16: Histogram of crossbeam icing at different wind speeds. (**a**) \(-15\,^{\circ}\)C, \(0\) m/s. (**b**) \(-15\,^{\circ}\)C, \(4.5\) m/s.  
As can be seen from Figure 17, the internal temperature of the beam increased at a faster rate in the time range of 0-4 h in the tests for condition 5, condition 6, and condition 7, with the rate of temperature increase decreasing from that occurring at 0-4 h in the tests for condition 5 and condition 6 at 4-6 h and stabilizing at 6-8 h; the rate of temperature increase began to stabilize in the tests for condition 7 at 4-8 h. The temperature rise test results of the average internal temperature of the electrically heated beam specimens at different ambient temperatures are shown in Table 7, after 8 h of heating, the average temperatures of the temperature measurement points in the tests for condition 5, condition 6, and condition 7 were 20.28 \({}^{\circ}\)C, 13.36 \({}^{\circ}\)C, and 6.04 \({}^{\circ}\)C, respectively. The test data show that the lower the ambient temperature, the lower the temperature reached after the beam was heated and stabilized, and the slower the rate of temperature rise.  
This is because the carbon fiber hot wire buried inside the beam model transfers heat to the surrounding area, and group B is midway between groups A and C. Therefore, the temperature of the temperature measurement point of group B is higher than that of both groups A and C. As group C is on the lower surface of the side of the beam, where the root of the icicle is mainly formed, group C best represents the lowest temperature of the surface of the carbon fiber hot wire under ideal conditions.  
Figure 17: _Cont._