## 5 Conclusions  
Utilizing full-scale model tests, the flexural behavior of Ultra-High-Performance Concrete (UHPC) wet joints with variable cross-section precast reinforced concrete bridge decks under negative bending moments was investigated. The following conclusions were drawn from experimental analysis:  
1. During loading, cracking initially occurred at the interface between new and old concrete of the wet joint, with a maximum crack width of 0.24 mm. As the load increased, minor cracks appeared on both sides of the wet joint, and cracking occurred at the bottom of the deck at the loading location, with a maximum crack width of 0.34 mm. The specimen ultimately failed near the variable cross-section location adjacent to the wet joint. The initial cracking load was 0.27 times the failure load (225 kN), with a failure load of 822 kN, and the maximum displacement was 21.64 mm.
2. Apart from the interface between new and old concrete, no cracks appeared at other locations of the wet joint, indicating that the use of UHPC wet joints with variable cross-section bridge decks significantly improves crack resistance under negative bending moments, meeting design requirements with good mechanical performance. The most critical position for wet joint failure in variable cross-section bridge decks is at thinner deck thicknesses and their variable cross-section locations.
3. In contrast to the failure pattern of uniform cross-section bridge decks, where failures often occur at wet joint locations, the failure mode of variable cross-section precast reinforced concrete bridge decks with UHPC wet joints involves flexural-shear failure near the variable cross-section of the wet joint. Vertical cracks initiate at the bottom of the deck and propagate upwards, evolving into diagonal cracks. From a lateral view, a major diagonal crack rapidly forms and extends to the edge of the load-bearing pad, ultimately resulting in the concrete specimen tearing into two parts and losing its load-bearing capacity.  
Figure 17: Comparison of damage results.  
* Displacement variation computed by the finite element model closely matches experimental results: both exhibit similar ultimate bearing capacities and ultimate displacements, with errors not exceeding 10%. Moreover, both follow similar load-displacement variation patterns, divisible into three stages. Employing the plastic damage model of concrete materials in ABAQUS software effectively identifies the position of plastic damage in the model. While this model cannot precisely pinpoint crack locations, it aids in determining damage locations and predicting the formation and propagation of cracks, with simulated concrete damage locations closely resembling experimental crack initiation and failure locations.  
Conceptualization, J.Y.; Methodology, [PERSON]; Resources, [PERSON]; Writing--original draft, [PERSON]; Supervision, [PERSON] All authors have read and agreed to the published version of the manuscript.  
National Natural Science Foundation of China, Funding Number: 52278159.  
Not applicable.  
The raw data supporting the conclusions of this article will be made available by the authors on request.  
This study was funded by the National Natural Science Foundation of China, Funding Number: 52278159. We are grateful to [PERSON] and [PERSON] for providing us with the necessary experimental sites and for working closely with us on the study and the design of the experimental protocol.  
The authors declare no conflict of interest.