Mechanism of Load Transfer and Deformation Coordination for a Novel Sliding-Type Connection Structure in Bridge Widening: Model Test and Numerical Investigations

In the lateral joint widening projects of multi-span continuous concrete box girder bridges, significant differences in longitudinal shrinkage and creep deformation, as well as vertical deformation incompatibility between the new and old bridges, can easily lead to stress concentration within the structure, causing concrete cracking. This is particularly evident in the form of substantial overall lateral bending deformation of the structure, which affects the safety and reliability of the widened bridge. To address this common challenge, this paper proposes a novel sliding-type transverse connection structure. This structure allows the longitudinal shrinkage and creep deformation of the new bridge’s main girder to occur independently from that of the old bridge through a sliding mechanism. As a result, it effectively accommodates longitudinal deformation differences, significantly reducing both stress concentration and overall bending deformation caused by such discrepancies. To further verify its feasibility and load transfer mechanism, scaled model tests and finite element analyses were conducted. The results demonstrate that this connection structure not only effectively coordinates longitudinal deformation differences between the new and old bridges and accommodates vertical deformation between their flange plates, but also achieves efficient transverse load transfer through shear force transmission. The design of the structure is primarily governed by shear stress . These research findings indicate that the sliding-type transverse connection structure can significantly improve deformation coordination issues in bridge widening projects, ensuring good mechanical performance and safety reliability of the structure.