Effects of grouting defects on the mechanical performance of half-grouted connections at low and normal temperatures

This paper reports the results of an experimental study on the mechanical performance of half-grouted connections at low and normal temperatures. Thirty-five groups of half-grouted sleeve connection specimens were prepared and subjected to uniaxial tension, reversed tension, and high-stress compression testing. The test variables included the grouting defect position, defect length, grouting type, rebar offset, and loading type. Defect location was found to play an important role in the failure modes of the connections. As the defect location moved from one end of the connection to the middle, the failure mode changed from tensile fracture failure of the rebar to debonding failure between the rebar and sleeve. The defect length was found to be critical in determining the failure modes of the connections. For a defect length of one rebar diameter and twice the rebar diameter, the typical connection failure mode was tensile fracture failure of the rebar. When the defect length was up to three times the rebar diameter, debonding failure occurred between the rebar and sleeve in most connections. The grouting defects caused limited damage to the tensile capacity of the connections, with a maximum decrease of 5.2% in the specimens subjected to uniaxial tension and a maximum decrease of 10.7% in the specimens subjected to reversed tension and high-stress compression. The grouting defects however caused severe damage to the deformability of the connections, with a maximum decrease of 52.5% in the specimens subjected to uniaxial tension and a maximum decrease of 59.5% in the specimens subjected to reversed tension and high-stress compression.