Research On Ultrasonic Testing And Capacity Assessment Of Sleeve Connectors Based On Grouting Compactness

The sleeve grouting quality of fabricated buildings belongs to black box.In practical construction,the factors affecting grouting quality of beam-reinforcement sleeve are not easy to control,and some sleeves with top void defects seriously affect the quality safety of joints and structures for fabricated buildings.At present,foreign scholars mainly investigate on the monotonically tensile properties based on the sleeve processing technology,shape and internal structure.Ultrasonic testing method based on grouting compactness has not been reported.In recent decade,the grouted sleeve technology has been studied in China,but it mainly focuses on monotonically tensile properties based on age,reinforcemen type,sleeve shape and internal structure,such as failure modes of connector,tensile capacity,steel strain,the external surface strain of sleeve,and capacity assessment of sleeve connectors based on grouting compactness is not reported.Regarding the problems above,this thesis investigated on ultrasonic testing and tensile capacity assessment of sleeve connectors based on grouting compactness,and the main research works and achievements are as follows:(1)To test the compactness of beam-reinforcement grouted sleeve during construction,and improve the assembly quality and safety of fabricated buildings,this thesis proposes an ultrasonic probability method based on t-distribution that is suitable for small sample detection of grouted sleeve compactness.The test of grouted sleeve compactness is carried out by 60 specimens in 3 cases to verify the feasibility and effectiveness of the method.The experimental results show that:the ultrasonic probability method based on t-distribution can not only reduce the workload while not decreasing the effect of defect detecting,but also increase the detection efficiency.(2)In order to study the tensile capacity of sleeve connectors,four kinds of sleeve connectors are monotonically stretched at 100%,90%,70%and 50%compactness level,respectively.The model of bond-slip capacity of reinforcement-grout is deduced by fitting data of monotonically tensile test,and thus the tensile capacity calculation formula of sleeve connectors is proposed.The results show that the tesile capacity of sleeve connectors decreases more obviously with the drop of grout compactness.The analytical value Pu.c is in agreement with the experimental result Pu,c for the tensile capacity.(3)Taking into account human,material,financial and experimental conditions and other restrictions,a finite element simulation is carried out to lay the foundation for the analysis of parameters and the expansion of test results for other researchers.Based on the monotonically tensile test and the unidirectional tensile test,the finite element model is simulated and the model output patterns are analyzed and discussed.The studies show that the simulation results,namely load-displacement curves,stress distribution and plastic equivalent strain are very close to experimental results,respectively,The studies in this thesis can provide a testing method and technique to solve the testing problem of grouting quality of grouted sleeve connectors in construction stage.The proposed connector tensile capacity assessment method enriches domestic research on grouted sleeve technology,and provid experimental data and technical support for relevant departments.In addition,the attempt to simulate the finite element model provides experience for other researchers to perform parameter analysis and extend the test results.