## 7 Conclusions  
1. In this paper, the local stresses on the girder segments supported on the top of the pairs in the maximum cantilever state were analyzed by establishing a finite element model of the steel box girder in the maximum cantilever state during incremental launching construction. The analysis results indicated that the local force of the steel box girders met the requirements, and the jacking could be carried out smoothly.
2. By simulating the unsynchronized vertical jacking and lateral offset occurring during incremental launching construction in the above model, the local stress changes in the girder segments under the separate effects of unsynchronized vertical jacking and lateral offset were analyzed. When unsynchronized vertical jacking occurred, the beam generated a bias load (the side with the smaller jacking height was subjected to a larger reaction force) and the local maximum equivalent force became larger with an increase in the difference in the jacking height. The sensitivities of different stress components to unsynchronized vertical jacking were different, and the diaphragms and longitudinal stiff ribs of the base plate were more sensitive to unsynchronized vertical jacking. When lateral offset occurred, the local maximum equivalent stress occurred in the contact area between the base plate and the pad, and increased with an increase in the lateral offset distance, even approaching the yield stress of the steel and seriously affecting the structural safety. Therefore, thresholds for the synchronization control of incremental launching shall be established and strictly monitored and corrected in a timely manner.
3. By calculating the local stresses in the beam when unsynchronized vertical jacking and lateral deflection occurred simultaneously in the beam, it could be found that the beam met the control requirements when the vertical jacking was unsynchronized vertical jacking or when the lateral deflections individually reached a certain value; however, when the two acted together, the local stresses in the beam may still have exceeded the safe range. Against the problem that the single-parameter control of synchronicity misses unfavorable states, this paper proposed the two-parameter control of top thrust synchronization, fitting the maximum equivalent stress under two-parameter co-action, and the permissible stress of Q345 qD steel was used as the limit value to obtain the two-parameter control equation of jacking synchronization, determine the control threshold of unsynchronized vertical jacking as 15 mm, and calculate the corresponding control threshold of lateral deflection according to the control equation to realize the dynamic control of lateral deflection.  
Figure 14: Dual-parameter dynamic control range.  
**Author Contributions:** Conceptualization, Q.L.; Methodology, H.G.; Software, H.G.; Formal analysis, H.G.; Writing--original draft, H.G.; Writing--review & editing, B.G. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research received no external funding.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The data presented in this study are available on request from the corresponding author. The data are not publicly available due to privacy restrictions.  
**Conflicts of Interest:** The authors declare no conflict of interest.