## 4 Static Performance Analysis  
The static analysis of the new composite tall-pier bridge is implemented in Midas Civil2019. The P-\(\Delta\) effects are incorporated into the analysis of the construction process.  
According to the Technical Specification for Concrete-Filled Rectangular Steel Tubular Structures (CECS 159:2004) in China [37], the bending moments of the principal plane of a rectangular CFST column should meet the requirements of Equations (2) and (3) simultaneously:  
\[\frac{N}{N_{\text{un}}}+(1-\alpha_{\text{c}})\frac{M}{M_{\text{un}}}\leq\frac {1}{\gamma} \tag{2}\]  
\[\frac{M}{M_{\text{un}}}\leq\frac{1}{\gamma} \tag{3}\]  
where \(N\) represents the design value of the axial compressive force; \(M\) is the design value of the bending moment; \(\alpha_{\text{c}}\) is the working load factor of the concrete; \(N_{\text{un}}\) is the designed value of the sectional vertical load-bearing capacity; \(M_{\text{un}}\) is the design value of the sectional flexural capacity; \(\gamma\) is the importance coefficient, which is taken as 1.1. At the same time, Equation (4) should also be met to ensure the out-of-plane stability:  
\[\frac{N}{\phi N_{\text{un}}}+\frac{\beta M}{1.4M_{\text{un}}}\leq\frac{1}{\gamma} \tag{4}\]  
where \(\phi\) is the compression stability coefficient; \(\beta\) is the equivalent bending moment coefficient.  
Table 2 lists the design combination of the forces of the new composite tall pier under the basic load combination. The checking results, also shown in Table 2, indicate that the four-limb CFST columns meet the requirements of the load-carrying capacity and stability. According to the analysis results, the maximum Von Mises stress of the EDMSPs under the basic load combination is 67.6 MPa, which is less than the design yield stress of 100 MPa. Hence, the EDMSPs remain elastic.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Critical Section**} & \multirow{2}{*}{**Load Type**} & \multicolumn{2}{c}{**Design Internal Forces**} & \multirow{2}{*}{**Notes**} \\ \cline{3-4} \cline{5-5}  & & **Axial Force (kN)** & & **Moment (kN\(\cdot\)m)** \\ \hline \multirow{4}{*}{\begin{tabular}{c} Left limb \\ (top) \\ \end{tabular} } & Maximum axial force & 15461 & \(-\)3468 \\  & Minimum axial force & 4368 & \(-\)1753 \\  & Maximum moment & 4626 & \(-\)1324 \\  & Minimum moment & 15202 & \(-\)3897 \\ \hline \multirow{4}{*}{\begin{tabular}{c} Left limb \\ (bottom) \\ \end{tabular} } & Maximum axial force & 13064 & 924 \\  & Minimum axial force & 1967 & 2373 \\  & Maximum moment & 6419 & 3392 \\  & Minimum moment & 8612 & \(-\)95 \\ \hline \multirow{4}{*}{\
\begin{tabular}{c} Right limb \\ (top) \\ \end{tabular} } & Maximum axial force & 13265 & \(-\)2820 \\  & Minimum axial force & 3181 & 2731 \\ \cline{1-1}  & Maximum moment & 5521 & 2853 \\ \cline{1-1}  & Minimum moment & 10163 & \(-\)3047 \\ \hline \multirow{4}{*}{
\begin{tabular}{c} Right limb \\ (bottom) \\ \end{tabular} } & Maximum axial force & 20660 & \(-\)635 \\ \cline{1-1}  & Minimum axial force & 8613 & 2788 \\ \cline{1-1}  & Maximum moment & 12887 & 3588 \\ \cline{1-1}  & Minimum moment & 15376 & \(-\)1317 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Design internal forces and checks of CFST Columns.