Grouted sleeve connectors are critical components in precast concrete structural joints. This study investigates the effects of grouting defect location, quantity, and grout strength on the bond–slip constitutive relationship at the steel–grout interface in fully grouted sleeves. Fifteen centrally loaded pull-out specimens were designed using the controlled variable method and tested under monotonic tension. Failure modes, ultimate load, bond stress, and slip characteristics were analyzed. Numerical modeling was performed using ABAQUS, and a mathematical bond–slip constitutive model was developed. The experimental results show that all specimens with a single defect failed by tensile fracture of the reinforcing bar, whereas those with multiple defects exhibited bar pull-out failure, which most significantly degraded connection performance. Grout strength positively correlated with interfacial bond performance. Deviation of the water-to-binder ratio from the standard value reduced grout strength, leading to decreases in bond strength, ultimate load, and slip. The apparent increase in bond stress under multiple defects was attributed to the reduced effective anchorage area rather than enhanced interfacial bonding, resulting in the lowest actual ultimate load among all scenarios. The established bond–slip constitutive model achieved a coefficient of determination R2 ≥ 0.96, indicating excellent fit. The finite element simulations agreed well with test data and accurately reproduced the bond–slip response under various defect conditions. The proposed constitutive model and finite element modeling approach provide a theoretical and quantitative basis for performance assessment of grouted sleeve connectors in engineering practice.
Zhang et al. (2026) studied this question.