EXPERIMENTAL RESEARCH ON MECHANICAL PROPERTIES OF NEW AND OLD CONCRETE JOINTS OF PREFABRICATED STRUCTURE

In the prefabricated bridge structure, the existing socket connection between the prefabricated pier and the bearing platform has no reinforcement passing through the joint interface, which has the problem of insufficient bond performance. In the paper, a new type of interface connection was proposed, namely the interface embedded distributed steel fiber connection technique. In order to study the influence of this new type of joint on the bond performance of new and old concrete interface, double-sided shear test and axial tensile test were designed respectively, and six test conditions were formulated, including integral pouring of plain concrete, integral pouring of reinforced concrete, chiseled connection of C40-C40 interface, chiseled connection of UHPC-C40 interface, embedded wave-shaped/end-hook-shaped steel fiber connection of UHPC-C40 interface, and the shear and tensile capacity of the interface were tested. The results showed that the shear bearing capacity of the steel fiber connection specimen was significantly higher than that of the chiseling treatment and the whole pouring of plain concrete, which is up to 86.5% of the whole pouring of reinforced concrete; the tensile bearing capacity of the steel fiber connection specimen was also significantly improved, and the UHPC-C40 interface was not cracked when the specimen was broken. In this paper, the feasibility of embedded distributed steel fiber technique for UHPC-NC new and old interface was preliminarily verified, and the shear strength and tensile strength of the joint could be effectively improved.