Experimental investigation of mechanical behaviour of rebar in steel half-grouted sleeve connections with defects in water/binder ratio

Abstract

The mechanical behaviours of the rebar in steel half-grouted sleeve connections with constructional deficiencies in the water/binder grout ratio were experimentally investigated in this study. The experimental variables were the rebar diameter, which varied from a small value of 12 mm to a large value of 20 mm, and the water/binder ratio of the grout, which ranged from 0.12 to 0.24. Six groups of steel half-grouted sleeve specimens were manufactured and tested under a tensile load to ascertain the failure mode, ultimate bearing capacity, strain distribution, and damage depth. The results indicated that the load–displacement responses of all the specimens were similar. Specifically, the specimens exhibited a linear elastic range, yield range, strain-hardening range, and necking range. The displacements at the yield and failure points, the tensile strain of the sleeve surface, and the depth of the damage at the grouting end all increased with the rebar diameter. High water/binder ratios led to bond failure and increased the damage depth at the grouting end. The hoop strain near the vent hole gradually changed from a compressive strain to tensile strain. An analytical model was established and verified to predict the ultimate bearing capacity of the specimens, considering the effect of the water/binder ratio; the bearing capacities of the specimens with high water/binder ratios were in agreement with the experimental data.