## 5 Comparative Analysis of Incremental Launching Monitoring Results
### Stress Monitoring of Steel Box Girder  
Table 4 shows the key stress monitoring values and calculated values of steel box girders under five working conditions. Table 4 indicates that the stress values are all within the limit range, which meets the monitoring and control requirements, meaning that the incremental launching operation can be carried out smoothly. Additionally, the elevated summer temperatures and the impact of on-site construction conditions contribute to a significant discrepancy between the monitored and calculated values.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Condition**} & \multirow{2}{*}{
\begin{tabular}{c} **Measuring** \\ **Point** \\ \end{tabular} } & \multirow{2}{*}{**Monitoring Data (MPa)**} & \multirow{2}{*}{**Calculated Value (MPa)**} & \multirow{2}{*}{**Limiting Value (MPa)**} \\ \hline \multirow{4}{*}{1} & D\({}_{24}\) & \(-9.8\) & \(-15.2\) \\  & G\({}_{12}\) & \(0.2\) & \(1.5\) \\  & G\({}_{15}\) & \(-13.8\) & \(-36.9\) \\  & G\({}_{32}\) & \(-1.6\) & \(-0.3\) \\ \hline \multirow{4}{*}{2} & D\({}_{24}\) & \(-65.8\) & \(-20.2\) \\  & G\({}_{12}\) & \(30.8\) & \(2.8\) \\  & G\({}_{15}\) & \(-52.0\) & \(-69.5\) \\  & G\({}_{44}\) & \(-17.6\) & \(13.2\) \\ \hline \multirow{4}{*}{3} & D\({}_{24}\) & \(41.4\) & \(17.2\) \\  & G\({}_{12}\) & \(-2.8\) & \(-0.4\) \\  & G\({}_{15}\) & \(-14.4\) & \(-18\) \\  & G\({}_{44}\) & \(3.4\) & \(5.9\) \\  & G\({}_{55}\) & \(6.6\) & \(-4\) \\ \hline \multirow{4}{*}{4} & D\({}_{24}\) & \(44.4\) & \(22.2\) \\  & G\({}_{12}\) & \(3.6\) & \(0.3\) \\  & G\({}_{44}\) & \(30.6\) & \(-51.8\) \\  & G\({}_{52}\) & \(55.4\) & \(0.3\) \\  & G\({}_{55}\) & \(37.2\) & \(-4.4\) \\ \hline \multirow{4}{*}{5} & D\({}_{24}\) & \(22\) & \(-19.6\) \\  & G\({}_{12}\) & \(-3.8\) & \(0.2\) \\ \cline{1-1}  & G\({}_{44}\) & \(21.4\) & \(-13\) \\ \cline{1-1}  & G\({}_{52}\) & \(13.8\) & \(0.5\) \\ \cline{1-1}  & G\({}_{55}\) & \(5.4\) & \(-3.8\) \\ \hline \hline \end{tabular}
\end{table}
Table 4: Contrast between measured and calculated stress in steel box girder.  
Figure 12: The settlement of incremental launching pier L3’s concrete foundation.  
According to Figure 13b, in the second phase of incremental launching, column Z\({}_{1}\) is almost in full tension, and the maximum stress is 85.2 MPa. As the incremental launching distance increases, the stress of column Z3 shows an overall increasing trend, and it remains in a compressed state throughout the process. Z2 is also under compression during the entire process, with a relatively stable stress that generally exhibits an increasing trend. In the second stage of incremental launching, with the increase in incremental launching distance, the stress of Z\({}_{1}\), Z\({}_{2}\), and Z\({}_{3}\) gradually increases; the maximum tensile stress is 85.2 MPa, and the maximum compressive stress is 124.8 MPa.  
It can be seen from Figure 13c that columns Z\({}_{1}\) and Z\({}_{2}\) are first compressed, and this gradually changes to tension after the incremental launching distance reaches unfavorable working condition 3, and the stress curve is relatively stable. Z\({}_{3}\) is compressed in the whole process, and the stress increases first and then decreases. When the incremental launching distance reaches 36 m, the stress of Z\({}_{1}\), Z\({}_{2}\), and Z\({}_{3}\) fluctuates. When the incremental launching distance is about 36-42 m, the stress of Z\({}_{3}\) fluctuates greatly and is more dangerous. The maximum stress reaches 178.6 MPa, and the stress gradually decreases after 42 m. In the third stage of incremental launching, the maximum stress at each incremental launching distance almost appears on Z\({}_{3}\), and the maximum compressive stress is 178.6 MPa.