Research On The Tensile Property Of New Type Grouting Sleeve With Large Diameter Considering Grouting Defect

The fabricated concrete building can effectively improve the development barrier of construction industry,which is consistent with the concept of green sustainable development.In recent years,the prefabricated concrete structure has rapidly spread in China with its unique advantages.Under the guidance of the government,all regions have encouraged and guided their development.Assembled construction has already begun to show results.The steel bar grouting sleeve connection widely used in the assembled concrete structure,there are a large number of horizontal and vertical mounting joints between the different components.The connection quality of the grouting sleeve and the construction quality of the installation joint are particularly critical,which directly affects the safety and service life of the whole building.In this paper,the experimental,theoretical and simulation analysis method is combined to explore the mechanical performance of the new large-diameter grouting sleeve considering grouting defects.The main results are as follows:Through unidirectional tensile test,the mechanical properties of 28 grouting sleeve specimens with grouting defects were studied.(1)the failure forms of the specimen include steel bar pulling and steel bar pulling out.(2)the load-displacement curves of different defect sizes of four different defect types,namely,end defect,internal concentrated defect,uniformly defect and defect thickness,were obtained;(3)internal defects have a greater impact on the mechanical properties of the specimens than the end defects;In the internal defects,the larger the number of defects,the smaller the bearing capacity of the specimen,the larger the defect thickness,the larger the variation within a certain range,and then tends to be stable.The bond strength of grouting materials is studied through theoretical analysis.(1)the bond strength value of grouting materials calculated by elastic mechanics theory and Mander model is not significantly different from the experimental value,which proves that the theoretical analysis is reasonable.(2)the influence coefficients of compressive strength of confined grouting materials for different defect types were proposed,and the values under various conditions were calculated;(3)the anchorage length requirements of reinforcing bars with different types of grouting sleeves with different defects were calculated respectively to provide a reference basis for actual engineering qualityevaluation.Through ABAQUS finite element analysis software,the mechanical performance and mechanical mechanism of grouting sleeve specimens with grouting defects were studied.(1)the load-displacement curve obtained by the finite element analysis is basically consistent with the trend of the test curve,with little difference in the ultimate bearing capacity,proving that the simulation analysis can better reflect the mechanical performance of the sleeve;(2)the internal grouting defect model needs to reduce the bond slip parameters between the reinforcement and the grouting material;(3)the stress mechanism and stress distribution law of the inner and outer sides of the grouting material under the condition of defect were obtained.