Experimental and numerical analysis of the effect of parallel-threaded connection geometry and normalisation on the cracking performance of reinforced concrete ties

This study aims to improve the understanding of the behaviour of reinforced concrete ties incorporating mechanical couplers. Although several connection methods for reinforcing bars have been proposed, the performance of parallel-threaded couplers (PTC) in reinforced concrete elements—particularly in terms of load transfer and cracking behaviour—remains insufficiently investigated. Tensile tests were carried out on reinforced concrete ties with different reinforcement configurations, including PTC of various geometries. Advanced measurement techniques, such as digital image correlation (DIC), were employed to monitor and analyse crack initiation, propagation, and opening under tensile loading. The results indicate that the geometrical characteristics and manufacturing processes of the couplers significantly affect the cracking response of reinforced concrete elements. Notable differences were observed in the initiation load of the first crack, the state of cracking, and the width of crack openings. In parallel, a numerical model was developed using ABAQUS to simulate the tensile behaviour of reinforced concrete ties with threaded mechanical couplers and was validated against the experimental results. The model provides insights into how the normalization process of the connection influences stress distribution and crack development. • Compact connections improved first crack load by 12 % vs. Eurocode 2 standards. • Slender connections reduced crack resistance by 47 % with 67 % larger openings. • Normalised connection process eliminates stress concentrations at connection ends. • FEM modeling validated experimental findings using Concrete Damaged Plasticity. • Results enable optimized mechanical splice design for high-risk structures.