Experimental Research on Mechanical Properties of Semi-Grouting Sleeve Connection After Being Subjected to High Temperature

The compressive strength of grout after high temperature was studied, and the formula for calculating the compressive strength of grout after being subjected to high temperature was derived. In order to study the mechanical properties of semi-grouting sleeve connection after of high temperature, the pull-out test of semi-grouting sleeve connection after being subjected to high temperature was designed with temperature, anchorage length and protective layer thickness as variables. The test results showed that the failure mode of specimens changed with the increase of temperature, and the failure mode changed gradually from steel bar fracture failure to steel bar pull-out failure. Increasing anchorage length could effectively improve the mechanical properties of semi-grouting sleeve connections. At 600℃, the ultimate load and ultimate displacement losses of specimens with anchor length of 120 mm were 6% and 46% respectively, which were far smaller than those of specimens with anchor length of 100 mm. The existence of protective layer was beneficial to improve the bearing capacity and ductility of semi-grouting sleeve connections. Based on the test results, the bearing capacity formula of semi-grouting sleeve connection after being subjected to high temperature was deduced, and the predicted values were in good agreement with the test values.