Numerical analysis on tensile capacity of loop connections

Cast-in-place joints are commonly used as an on-site connection for precast assembled bridge concrete elements. The reinforcements in traditional cast-in-place joints usually are tied or welded, which takes more time and increases construction time. With advantages of the construction convenience and the small joint length, loop connections are gradually adopted by recent practice engineering. The strut-and-tie model is currently often used to calculate the tensile capacity of loop connection, but the current model based on geometric structure fails to consider the influence of the adjacent U-bars and the transverse reinforcements. In this paper, numerical models of loop connections are established and verified with the experiments to reveal the effect of the adjacent U-bars and the transverse reinforcements. Parametric analyses are then developed to reveal the force mechanism of loop connections. Finally, a modified strut-and-tie model considering the effective strength and the width of the concrete compressive strut is proposed, and the simplified calculation method of tensile capacity of loop connections is proposed.