Experimental study on the tensile behavior of ultra‐high performance concrete fiber continuous joints

Abstract The application of ultra‐high performance concrete (UHPC) in the bridge deck effectively increases the strength, ductility, and durability of the deck system, while the problem of fiber discontinuity at the joint‐deck interface remains unsolved. This study proposes an innovative UHPC joint to create steel fiber continuity at the interface and experimentally investigates its tensile behavior. Test parameters include fiber content, fiber length and diameter, fiber shape, and fiber strength. Test results indicate that the joint tensile strength increases with fiber content, fiber length, and fiber strength. The specimen with hooked end fibers also develops higher joint tensile strength compared with the specimen with straight fibers. It is recommended to use fibers with a smaller diameter to increase the interfacial bonding area between the fibers and the matrix. High‐strength fibers are also recommended to achieve the best efficiency in a high‐strength matrix, like UHPC. The tensile performance of the joint with a fiber content of no less than 0.5%, and an embedment length of 15 mm (with a fiber length/diameter ratio of 50), and a diameter of 0.3 mm is similar to the performance of the specimen cast as one piece. Therefore, a properly designed UHPC fiber continuous joint is recommended in engineering practice to improve the integrity of the joint‐deck system.