Flexural performance of UHPC-filled narrow joints between precast concrete bridge slabs

The deck slabs narrow joints in concrete bridges filled with Ultra-high performance concrete (UHPC) have the potential for wide application and high-efficiency promotion, but there is limited research available on this topic. This paper conducted flexural tests on the new joints. Ten precast concrete deck panels were designed and manufactured for concrete bridges. These panels were connected using UHPC-filled narrow joints. Combined with stress analysis, this study investigates the influence and mechanism of various factors on the mechanical performance of UHPC joints. These factors include the geometric shape of the joint, the roughness of the joint interface, the filling material used in the joint, the width of the joint, and the configuration of joint reinforcement (including the shape and length of lap reinforcement). The test results show that the panel with the UHPC joint filled with steel fibers has excellent flexural and bonding capacity. The jointed panel with a lap length of 140 mm and 120 mm has better flexural performance than the one with a lap length of 90 mm. The straight-jointed panel has a higher flexural capacity compared to the complex triangular-jointed panel. Additionally, reducing the joint width can achieve similar mechanical properties as before. A method has been proposed for calculating the flexural capacity of a jointed panel, utilizing the strut-and-tie model (STM). This method can accurately predict experimental results.