Mechanical behaviours of heat-damaged grouted sleeve connections

An experimental study with 72 specimens was conducted to determine the effects of various factors on the mechanical behaviours of grouted sleeve connections, including an increase in temperature from 20 °C to 600 °C, the loading regime (uniaxial tensile loading or cyclic loading), and the grout compressive strength (83.1–91.1 MPa). After the specimens were exposed to elevated temperatures of up to 600 °C and then uniaxial tensile loading or cyclic loadings, the experimental results indicated that the sleeve was still elastic and the grout had a compressive strength of more than 83.1 MPa, which was beneficial for maintaining the mechanical behaviours of the specimens. In this study, the sleeve region was equal to the gauge length, which consisted of the length of the sleeve and three times the diameter of the rebar from each end of the sleeve. Moreover, a bilinear model was formulated to calculate the yield and ultimate loads of the heat-damaged grouted sleeve connections after different loading regimes. Finally, the constitutive relationship of the heat-damaged grouted sleeve connection was investigated. These findings will be helpful in the fire safety design of precast concrete structures.