## 5 Conclusions  
In this study, the causes of long-term deflection in large-span continuous prestressed concrete rigid-frame (CPCR) bridges were analyzed through field monitoring and refined modeling techniques. The main conclusions are summarized as follows:  
1. An accurate refined modelling approach that takes into account reinforcement behavior and various performance degradation behaviors has been elaborated to simulate the behavior of large-span CPCR bridges. The proposed finite element model has been validated by comparing predicted results with field monitoring data from a 270 m CPCR bridge in China over the past two decades, with a maximum error smaller than 5%.
2. A sensitivity analysis of different damage conditions on the CPCR bridge performance was carried out. It can be concluded that the primary cause for long-lasting deflection in large-span CPCR frame bridges is attributable to the time-dependent loss of longitudinal prestress. For the validated model proposed in this paper, the maximum vertical deflection increased by 190% when the longitudinal prestress loss reached approximately 30% in this model.
3. The sensitivities to the impact on the overall performance of the structure ranged from significant to slight: longitudinal prestress loss, box girder crack, concrete creep, continuous joint damage, horizontal and vertical prestress loss, and discrete joint damage, respectively.
4. The impact of joint damage was highly related to the span length of the bridge. In the case of a small span, the proportion of shear force acting on the beam becomes greater, thereby amplifying the significance of shear stiffness loss caused by joint damage. For long-span CPCR bridges, however, the section bending moment dominates and limits the effects of joint damage on structural integrity.
5. Local displacement and stress distribution are significantly influenced by typical structural damage, and the affected areas are different. For CPCR bridges with segmental joint damage, reinforcing the corresponding joint is sufficient to maintain bridge performance. Reinforcing the crack location alone is insufficient when structural cracks appear in the beam. Remediation measures must be tailored to the respective stress redistribution zones to prevent the further expansion of existing cracks.  
Conceptualization, X.H. and W.L.; methodology, X.H.; software/simulation, X.H. and P.L.; validation, X.H., W.L. and P.L.; formal analysis, X.H.; investigation, W.L. and P.L.; writing--original draft preparation, X.H.; writing--review and editing, W.L.; supervision, W.L.; project administration, P.L. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Research Institute of the Highway Ministry of Transport and the \"Key Technology Research of Guanfo Expressway Maintenance Engineering\" project (0222 KF06 SC1123).  
Not applicable.  
Data Availability Statement: Data from this study can be made available upon request.  
This work was funded by the \"Key Technology Research of Guanfo Expressway Maintenance Engineering\" project. In addition, we thank [PERSON] (X.Z.), who works in the Guangzhou-Shenzhen Expressway Reconstruction and Expansion Management Office, for help provided during the research.  
The authors declare no conflict of interest.