## 4 Proposed Methodology of Monitoring
### Stress and Internal Force Analysis  
Stress and internal force are the most important indexes to investigate the tower bearing capacity. Table 4 below shows the internal force and stress values of key sections under various working conditions, and presents a comparison between working conditions.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Project** & **Result** & **Condition 1** & **Condition 2** & **Regulation Rate of Change (\%)** \\ \hline \multirow{6}{*}{Matan Hongshui He Bridge} & Column steel pipe maximum stress (MPa) & 118.90 & 117.40 & 1.28 \\  & Tower top structure Maximum stress (MPa) & 122.10 & 122.70 & 0.49 \\  & Buckle anchoring maximum stress (MPa) & 88.60 & 89.50 & 1.01 \\ \cline{1-1}  & Tower top shaft force (kN) & 219.70 & 337.80 & 34.96 \\ \cline{1-1}  & Base of the tower shaft force (kN) & 2679.50 & 2870.10 & 6.64 \\ \cline{1-1}  & Tower top bending moment (kN-m) & 290.72 & 282.90 & 2.76 \\ \cline{1-1}  & Bottom of the tower bending moment (kN-m) & 63.90 & 62.90 & 1.59 \\ \hline \multirow{6}{*}{Pingnan Third Bridge} & Maximum stress of column steel pipe (MPa) & 182.10 & 193.9 & 6.48 \\ \cline{1-1}  & Maximum stress of tower structure (MPa) & 60.20 & 61.9 & 2.82 \\ \cline{1-1}  & Maximum stress of tower web (MPa) & 62.11 & 64.00 & 3.04 \\ \cline{1-1}  & Internal force at the bottom of the tower (kN) & 3679.20 & 3769.10 & 2.44 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Stress and internal force under various working conditions.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
\begin{tabular}{c} Cable action, self-weighting, buckle load, 6 levels of \\ vertical wind, cable initial tension, active control force \\ \end{tabular} \\  & & & \\ \hline \hline \end{tabular}
\end{table}
Table 2: Various working conditions of construction.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Project** & **Injection** & **Condition 1** & **Condition 2** & **Regulation Rate of Change (\%)** \\ \hline \multirow{2}{*}{Matan Hongshui He Bridge} & Horizontal (mm) & 153.00 & 18.10 & \(-\)88.17 \\  & Vertical (mm) & \(-\)48.80 & \(-\)51.08 & 4.67 \\ \hline \multirow{2}{*}{Pingnan Third Bridge} & Horizontal (mm) & 185.22 & 17.07 & 90.78 \\  & Vertical d(mm) & \(-\)83.39 & \(-\)78.78 & 5.50 \\ \hline \hline \end{tabular}
\end{table}
Table 3: The calculated results of tower top displacement (mm).  
As the results show, the maximum stress for the tower of Matan Hongshui He Bridge in working condition 1 and 2 is 122.1 MPa and 122.7 MPa; the maximum stress for the tower of Pingnan Third Bridge in working condition 1 and 2 is 182.1 MPa and 193.9 MPa. As a whole, the effect of active control on the stress of the structure is not obvious. It is clear that the active control has a smaller impact on the stress of the structure. The active control force exerts obvious impact on the horizontal displacement of the tower, but it has very low sensitivity to the stress and internal force of the tower. According to the strength design value of CFST tower and the steel content ratio of the bridge tower, the maximum limit value is calculated to be 203 MPa, which meets the requirements of the specification and shows the tower is in a safe state.