## 3 Analysis of Engineering Example
### Database of Training Samples  
Because the lateral offset and the lifting height difference affect the beam stress by changing the action point of the support reaction force, in order to set the control thresholds for a lateral offset and jacking differences safely, it is first necessary to identify the location where the maximum support reaction occurs during the incremental launching process, simulate the occurrence of a lateral offset and jacking difference, and calculate the corresponding local maximum stress of the beam. In this study, a full-bridge truss finite element model of the third and fourth sections of the main girder was established using Midas Civil 2021 software, and an analysis of the incremental launching construction stage was conducted. The changes in support reactions at each pier were extracted, as shown in Figure 7. The calculation results indicate that the maximum support reaction occurs at Pier 148, with the main girder cantilevering 30 m beyond Pier 149 at that time; the working condition is CS26-2, as shown in Figure 8.  
Figure 5: Main beam cross-section. Figure 6: The third and fourth main girder facade layout. The buckling stability factors for the typical adverse working conditions and their adjacent conditions were calculated, and the results are shown in Table 2. From the calculation results, it can be seen that the stability factor of the beam under typical adverse working conditions meets the code requirements [27], and the structure will not experience buckling instability. Using Midas FEA NX 2021 software, based on the mixed element method, take the 8 m long girder section near Pier 148 under this condition for refined modeling; the remaining main beams and guide beams are still simulated by beam elements, and the two use the rigid domain for connection. The cushion block is simulated by the solid element. The material is rubber with an elastic modulus of 30 MPa, the main girder is made of Q345 qD steel, the weight is 7.85 \(\times\) 10\({}^{-5}\) N/mm\({}^{3}\), the elastic modulus is 210 GPa, the steel guide girder is made of Q345 steel, the weight is 7.85 \(\times\) 10\({}^{-5}\) N/mm\({}^{3}\), and the elastic modulus is 206 GPa. In order to simulate the possible bearing void phenomenon, the general contact is set between the cushion block and the base plate. The grid model is shown in Figure 9, and the stress cloud diagram of each main component is shown in Figure 10. \begin{table}
\begin{tabular}{c c} \hline
**Working Condition** & **Stability Factor** \\ \hline CS26-1 & 4.74 \\ CS26-2 & 4.28 \\ CS26-3 & 4.53 \\ \hline \end{tabular}
\end{table} 
Table 2: The stability factor of the typical adverse working condition. Figure 8: The working condition of the maximum support reaction force. \(\
ex  
According to the \"Code for design of steel and concrete composite bridges\" (GB50917-2013) [28], the design strength of the Q345 qD steel plate within 50 mm is 275 MPa, and the design strength of the Q420 qD steel plate is 335 MPa. Considering the point of view of bias safety, the design strength of the Q345 qD steel plate of 275 MPa is taken as the stress limit. Figure 10: Equivalent force cloud of members in the contact region. (**a**) Base plate equivalent force map. (**b**) Equivalent force map of the web. (**c**) Equivalent force map of stiffening ribs. (**d**) Ventral transverse septum iso-efficiency maps. Figure 9: Refined model of girder section near Pier 148. In order to simulate the simultaneous existence of a beam lateral offset and jacking difference in the process of an incremental launching construction, the phenomenon of a beam lateral offset in the incremental launching construction is simulated by adjusting the relative position of the cushion block and steel-box girder floor in the refined model. By applying a forced displacement in the Z direction (vertical bridge direction) to the bottom of the left (right) side of the cushion block, the vertical jacking asynchrony can be simulated.