# Model Experimental Study on De-Icing Method of Bridge Pylon Beam Based on Electric Heating
## 3 Pre-Tests of Icing and Analysis of Results
### Icing Features  
The icing test results were quantified to more accurately summarize the icing rule of the beam, thereby verifying the reliability of the test conditions and providing standards for subsequent anti-icing tests. The distribution of the icicles was roughly drawn in the form of a histogram, as shown in Figure 10. Only the icicle length is shown in the figure; the diameter is ignored, and the spacing between the icicles is assumed to be equal. The vertical axis of the histogram represents the icicle length, and the horizontal axis represents the position on the beam. Among them, the length of the beam between the two supports is 1.5 m, which is the length of the horizontal axis. The supports on the left and right sides are used as the coordinate origin and end point, respectively. Moreover, the variation of the icicle size (length and diameter) is shown in Figure 11.  
The icicles on the beam were different in length, and the distribution of the long and short icicles was irregular. As can be seen in Figure 10a-c, as the ambient temperature decreases, the column density increases and the blank area decreases, meaning that the number of icicles increases and that the overall length of the icicles shows an increasing trend. When the ambient temperature reached \(-15\)\({}^{\circ}\)C, the distribution density of icicles reached a saturation state. Figure 10d,e present the icicle length distribution after applying wind. It can be seen that after the wind is applied, the distribution density of the icicles is still in a saturated state, but the blank area continues to decrease, indicating that the overall length of the icicles further increases. Overall, in the laboratory rainfall icing tests, with the continuous deterioration of the environment, the distribution density of the icicles on the beam will reach a saturation state, and the overall length of the icicles will continue to increase. The dimensions of the icicles are recorded in Table 3. A a columnar-dotted line composite graph of the changing of the size with the environment was drawn, as shown in Figure 11. It can be seen that both the length and the diameter of the icicles increase as the ambient temperature decreases. However, in the two different temperature ranges (\(-5\)\({}^{\circ}\)C to \(-10\)\({}^{\circ}\)C and \(-10\)\({}^{\circ}\)C to \(-15\)\({}^{\circ}\)C), the two growth rates of the icicles are obviously different. The increments of \(L_{\text{max}}\) and \(L_{\text{ave}}\) in the first temperature range were 13.4 cm and 3.99 cm, respectively. Due to the decrease in ambient temperature, a large amount of rainwater froze on the way to the icicle tip, resulting in the increments of the second interval being only 2.8 cm and 2.44 cm; thus, they decreased by 79.1% and 38.85%. Correspondingly, the diameter of the icicles showed the opposite trend. For example, the increments of \(D_{\text{max}}\) and \(D_{\text{ave}}\) in the first interval were 0.91 mm and 0.76 mm, respectively, and 2.91 mm and 1.17 mm in the second interval; thus, they increased by 219.78% and 53.95%. These data show that when the ambient temperature continues to decrease, the diameter and length of the icicle will increase, but the length increment will decrease; the diameter increment will increase instead, and the icicle will grow more in the radial direction. Figure 11: The icicle size variation with ambient temperature and wind velocity. **Note**: \(L_{\text{max}}\) is the maximum length; \(L_{\text{ave}}\) is the average length; \(D_{\text{max}}\) is the maximum diameter; \(D_{\text{ave}}\) is the average diameter. After the wind was supplied, the length and diameter of the icicles showed a similar growth rule. The growth trend of the icicle length changed from gentle to steep, while the wind velocity increased from 0 to 3 m/s.