Mechanical Behavior of Grouted Sleeve Butt and Lap Joints with Anti-Deflection Measures Under Uniaxial Tension and High-Stress Cyclic Loading

To compare the mechanical performance differences between sleeve grouting lap and butt joints, a total of 41 lap joints, including 27 standard lap joints and 14 anti-deflection lap joints, and 20 butt joints were subjected to tensile and high-stress cyclic tensile-compression tests. The results indicate that both types of joints failed by tensile fracture of the rebars in uniaxial tension, with the load-bearing capacity, total elongation at maximum force, and ductility generally meeting the code requirements. In high-stress cyclic tests, the load-bearing capacity of both types of joints increased, while the initial stiffness and ductility decreased. The residual deformation of the anti-deflection lap joints and butt joints generally met the specification requirements. Anti-deflection measures can reduce the residual deformation of lap joints; however, their constraint stiffness is limited, resulting in slightly greater residual deformation of lap joints compared to butt joints. After the completion of the high-stress cyclic tensile–compression tests, the maximum longitudinal strain near the reinforcement side of the sleeve’s middle cross-section in lap joints and the absolute value of the maximum circumferential compressive strain were both less than those in butt joints, indicating that lap joints have lower tensile performance requirements for the sleeve. Based on experimental results, a lap length of 12.5 d is recommended, with an additional 4–6 d allowance to enhance splice reliability under high-stress cyclic loading.