## 4 Determination of the Calculation Parameters of the Temperature Field
### Convection Heat Transfer Parameters  
The convective heat transfer between the main tower surface and the air is a complicated heat conduction phenomenon. The efficiency of convective heat transfer depends on many factors, such as ambient air temperature, wind speed, humidity, etc., so the relationship between them is usually determined through tests or empirical formulas [16]. In this way, the heat transfer between the surface of the main tower and the air can be more accurately calculated to analyze and predict the temperature field effect and heat conduction characteristics of the main tower [17]. Among the many influencing factors, wind speed is the most dominant influencing factor. As the wind speed (direction) is constantly changing, the higher the wind speed level is, the higher the heat transfer efficiency will be. Therefore, wind speed is generally used to determine the coefficient of convective heat transfer in the simulation calculation of the temperature field [18]. However, unified value corresponding to the convective heat transfer coefficient is inaccessible. Different values might be employed by different scholars, e.g., the values adopted by [PERSON] et al. [13], [PERSON] et al. [19], [PERSON] et al. [20] and [PERSON] et al. [21] are listed in Table 4.  
Based on the basic values provided in Table 3, the convection heat transfer coefficients on the outer surface of the main tower were all 13 W/m\({}^{2.\circ}\)C for simulation in the tempera  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**NamePosition** & **Roof** & **The Outer Surface** & **The Bottom** & **The Inner Surface** \\  & **Surface** & **of the Web** & **Surface** & **of the Box Girder** \\ \hline [PERSON] et al. [13] & 14.30 & 13.30 & 12.34 & 9.30 \\ [PERSON] et al. [19] & 15.23 & / & 15.14 & 10.20 \\ [PERSON] et al. [18] & 11.60 & 9.60 & 7.60 & 5.60 \\ [PERSON] et al. [20] & 11.40 & 9.50 & 7.60 & 5.70 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Convective heat transfer coefficient selected by scholars at home and abroad (W/m\({}^{2.\circ}\)C).  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Weight** & **Modulus of** & **Poisson’s** & **Coefficient of** & **Thermal Expansion** & **Thermal Capacity** & **Specific Heat** & **Heat Source** \\
**Density** & **Elasticity** & **Ratio** & **(1/\({}^{\circ}\)C)** & **(W/m)** & **(J/kg\({}^{\circ}\)C)** & **Coefficient** \\ \hline
26 & \(3.60\times 10^{4}\) & 0.2 & \(1\times 10^{-5}\) & 2.7 & 1176 & 1 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Basic thermal parameters of the concrete typed C60 [13].  
ture field effect analysis of the main tower. It is noted that, as the Nanjing Xinshengwei Yangtze River Bridge is under construction and installing sensors in the tower wall is not permitted, monitoring data for validating the finite element model is unavailable. However, the modelling method adopted in the present study is the same as the one adopted by [PERSON] et al. [22], in which the numerical results are compared to the test data of the solar radiation temperature field of the thin-walled concrete tower. Therefore, it is believed that the modelling method employed in the present study is feasible and the numerical results are acceptable.