Experimental investigation of uncertain factors on the mechanical properties of half-grouted sleeve connected with large-diameter high-strength reinforcement

Abstract

The half-grouted sleeve connection (HGSC) is widely used to connect reinforcement in precast concrete (PC) structures. While some studies have examined the mechanical behavior of the HGSC, there is still a lack of research on uncertain factors with large-diameter high-strength reinforcement. To fill this gap, an extensive experimental study was conducted to investigate the mechanical properties of the HGSC under monotonic tensile loads. The impact of various uncertain factors, including the embedded length, water-binder ratio (w/b) of the grouting material, eccentricity of rebar, thread diameter, and thread length, was investigated. It was found that the HGS connected with large-diameter high-strength reinforcement has four damage modes, i.e., thread fracture, thread pullout, reinforcement fracture, and bond-slip failure. Notably, to obtain the target of equivalent reinforcement, the dispersion ratio of the w/b should be controlled within 0.3, the embedded length should be greater than 6d, and the thread diameter and the thread length should not be less than 1d. Based on the HGSC investigated in this paper, a model for predicting the axial force and circumferential confining strain was presented, and a method was provided to calculate the elastic and plastic lengths for the embedded reinforcement. This study provides valuable guidance for the application of large-diameter high-strength rebar in PC structures.