Experimental Study on the Performance of the UHPC Stitching Joint Between New and Original Bridges

Abstract:

Based on the bridgestitching project of Jiyang viaduct, Shanghai, an experiment was conducted on highstrain hardening ultrahighperformance concrete (UHPC) stitching joints. Asymmetrical loading was used to simulate the bridge uneven settlement in the experiment. The experiment results show that the entire process can be divided into three stages: elastic stage, cracks developing stage and failure stage. First, cracks appear under the UHPC panels; then, many micro cracks appear on the side of the UHPC panels. The cracks appear in the form of microcrack clusters, and the crack width slowly increases. When the UHPC panel rotation is 1.2%, the crack width is 0.16 mm, so the UHPC has excellent crackcontrol ability. In the end, the main crack appears at the bottom of the UHPC panels, and the transverse reinforcements yield because the reinforcement layout satisfies the requirements of the failure mode of the specimen. Thus, the reinforcement arrangement of the specimen is reasonable. The experiment was simulated using the finiteelement model, and the results were coordinated with experiment results. The parameter analysis was carried out by the finite element method, and the results show that increasing joint free length and reducing joint thickness can effectively enhance the bending performance of joints. Because the advantages of the UHPC joint are convenience, rapidity, and excellent performance, a joint form based on the type of nonconnection of upper and lower structures is put forward. What’s more, a detailed reinforcement scheme is given, which will serve as a reference for similar projects in the future.