Comparison of tensile mechanical properties of half grouted sleeve connection at elevated and post-elevated temperature: An experimental study

Abstract

To systematically compare the mechanical properties of half sleeve grouted connections at elevated and post-elevated temperatures, this study conducted tensile mechanical performance tests on 27 half grout sleeve connections (HGSC). Furthermore, the mechanical index of the HGSC has been evaluated. Test results revealed unique failure mechanisms in specimens subjected to a high temperature of 800 °C, in contrast to those exposed to temperatures between 200 °C and 600 °C. Significantly, specimens exposed to elevated temperatures demonstrated a bond-breaking mechanism, resulting in the rebar detaching from the interior at temperatures up to 800 °C. Utilizing scanning electron microscopy (SEM), the state of grout following exposure to 800 °C has been assessed. The analysis revealed extensive fractures within the grout, spanning both the grout material and its underlying substrate. Post exposure to elevated temperatures, the specimens primarily exhibited two failure modes: the pulling of bars and their extraction from the ports. Compared to specimens at elevated temperatures, those post elevated temperatures exhibited a slower rate of decline in ultimate load. However, specimens at elevated temperatures showed a more pronounced decrease in the temperature range of 600 °C to 800 °C. The formula for bond stresses at elevated and post-elevated temperatures was derived through statistical regression, and specific recommendations were also given for the selection of anchorage lengths based on the test results.