The Experimental Research Of Semi-grouting Sleeves Splicing For Rebars After Exposed To High Temperature

Nowadays,the state vigorously develops the assembled structure,industrial mode of production has speeded up the pace of construction.At the same time,Fire causes great damage,not only make the country property suffer great losses,but also affect human's life.But the current specification which are both "Technical specification for precast concrete structures"(JGJ1-2014)and "Code for fire protection design of buildings"(GB50016-2014)do not mention the specific requirements of fire resistance in the assembled structure,and the quality of the connection parts is the key to ensuring the quality of assembled structure.So the experiment takes the joint which is connected by semi-grouting sleeves as the target to study on fire resistance.Ninety semi-grouting sleeves were designed in the research,and five temperature variables(room temperature,200 ?,300 ?,400 ? and 600 ?)were designed to simulate the high temperature state.By the uniaxial tensile test,it can be concluded the factors of anchorage length and thickness of protective layer and the sleeve material affect the tensile strength,and the relationship among the ultimate tensile force of semi-grouting sleeve and temperature and anchorage length was given.By the compression test and bending test,it can be concluded the temperature affects the concrete grouting material,and the relationship between compressive strength of grouting material and temperature was given.On the basis of the experimental results,the paper used the ANSYS to support the theoretical analysis and the test results.Through the experimental study and theoretical analysis,it is shown that the properincrease of the thickness of the protective layer and the length of the anchorage can effectively improve the fire resistance of the connecting part.The influence of the sleeve material on the fire resistance is not obvious,but from the economic point,the semi-grouting sleeves made by cast iron are more economical and practical.In this paper,the mathematical formula among the ultimate tension of the semi-grouting sleeves and temperature and anchorage length under the conventional protective layer is given.Therefore,the results of this paper have some reference value and practical significance for the prediction of the residual strength of the connected parts after fire,also provides the references of the fire design and construction for the joints of the assembled structure.