## 4 Analysis of Calculation Results
### Effects of Stiffness of the Main Girder  
Structural stiffness of partially cable-stayed bridges was generally dominated by main girder stiffness supplemented by stiffness of the tower and cable-stayed cables. The effects of changes in main girder stiffness on overall structural forces were first studied. Based on the finite element model of the bridge, the modulus of elasticity of the main girder \(E_{\text{G}}\) was changed and main girder stiffness taken as 0.2, 0.5, 1, 2, 3, 5, 8 and 10 times the original stiffness, while the other parameters remained unchanged. Comparisons of internal forces and deformations of the main girder and cable tower were performed. The findings are shown in Figure 4, where \(M\)/\(\sum\)\(M\)(%) and \(\gamma\)/\(\sum\)\(\gamma\)(%) represent the ratios of the bending moment and deformation of each critical part under current \(E_{\text{G}}\)\({}^{\prime}\)\(I_{\text{G}}\)/\(E_{\text{G}}\)\(I_{\text{G}}\) and the sum of maximum bending moment and deformation of each \(E_{\text{G}}\)\({}^{\prime}\)\(I_{\text{G}}\)/\(E_{\text{G}}\)\(I_{\text{G}}\) calculation group, respectively. To eliminate the differences in order of magnitude, unit, plus or minus of calculation results, the normalized dimensionless treatment was used [19; 20]; the expressions are  
\[y_{ij}=\frac{x_{ij}}{\sum_{i=1}^{m}x_{ij}} \tag{1}\]  
where \(x_{ij}\) is the \(j\)th raw data of the \(i\)-th group; \(y_{ij}\) is the result of dimensionless transformation of \(j\)th raw data of the \(i\)-th group; and \(m\) is the number of data in each group. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Methodal Performance**} & \multirow{2}{*}{**C60 Main Girder, Bridge Tower**} & \multirow{2}{*}{**C55 Bridge Pier**} & \multirow{2}{*}{**Steel Stranded**} & \multirow{2}{*}{**Epoxy Coated Steel Strand**} \\ \hline Elastic modulus/MPa & \(3.6\times 10^{4}\) & \(3.55\times 10^{4}\) & \(1.9\times 10^{5}\) & \(1.95\times 10^{5}\) \\ \hline Tension strength/MPa & — & — & \(1.86\times 10^{3}\) & \(2.0\times 10^{3}\) \\ \hline Poisson ratioy & 0.2 & 0.2 & 0.3 & 0.3 \\ \hline Coefficient of thermal expansion/\({}^{\circ}\)C & \(1.2\times 10^{-5}\) & \(1.2\times 10^{-5}\) & \(1.2\times 10^{-5}\) & \(1.2\times 10^{-5}\) \\ \hline Unit weight/(kN\(\cdot\)m\({}^{-3}\)) & 26.5 & 26.5 & 78.5 & 78.5 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Mechanical properties of finite element model materials. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Group**} & \multicolumn{2}{c}{**Main Girder**} & \multicolumn{2}{c}{**Stayed Cable**} \\ \cline{2-5}  & \(E_{\text{G}}I_{\text{G}}\)\({}^{\prime}\)/\(E_{\text{G}}I_{\text{G}}\) & \(l_{1}\)/m & \(l_{2}\)/m & **Diameter/mm** & **Pairs Number** \\ \hline
1 & 0.2, 0.5, 1, 2, 3, 5, 8, 10 & 18.6 & 67.4 & 93.46–106.41 & 19 (13) \\ \hline
2 & 1 & 18.6 & 67.4 & 29.55–132.17 & 19 (13) \\ \hline
3 & 1 & 18.6 & 67.4 & (31.31–140.03) & 19 (13) \\ \hline
4 & 1 & 18.6 & 67.4, 75.4, 83.4, & 93.46–106.41 & 19–15 (13–9) \\  & 1 & 91.4, 99.4 & (99.01–111.32) & 19–15 (13–9) \\ \hline \hline \end{tabular} Note: The diameter in brackets is 55-gs 15.2 cable diameter, pairs number in brackets is 4# tower diagonal cable quantity.  
\end{table} 
Table 2: Parameter value changes. In Figure 4, with increasing main girder stiffness, the main girder midspan bending moment and moment at the root of the main girder tower exhibited a large increasing trend. There were no significant changes in moment at the root of the bridge tower.