Experimental and numerical analysis on flexural behavior of U-bar loop connection with lap height

U-bar overlapping connections are currently widely used in precast segmented bridges and modular concrete systems. To promote the further application of U-bar in prefabricated structural support, and provide guidelines for design of U-bar loop connection, a total of nine specimens associated with lap length, lap height and joint concrete strength are designed and examined through four-point bending tests. Lap height is the height of the overlapping part of the U-bar overlap connection. The experimental results indicate that the lap length and lap height have a significant impact on the bearing capacity of U-bar wet joints. The bearing capacity of a lap length of 15d is 23.4 % and 16.3 % higher than that of 5d and 10d, respectively. The increase in lap height reduces the difference in load-bearing capacity between 15d and 10d to 6.8 %. The established finite element model can effectively simulate the failure of the specimen. Based on this model, a parametric analysis was conducted on the influence of lap length and lap height on the bearing capacity of specimens. The finite element results indicate that a sufficiently high lap height can offset the decrease in bearing capacity caused by insufficient U-bar lap length. Based on experimental and numerical simulation results, a calculation formula for the bearing capacity of U-bar joints considering the lap height is proposed, whose theoretical predictions and the test results differ by less than 10 %. In addition, a formula for calculating the minimum lap height of U-bar loop connection was proposed.