Study Of Bond Stress-slip Relationships Between Grout And Steel Bars In Shale Ceramsite Concrete

At present,the main structure form of the residential building in our country is precast assembly shear wall structure,and the key technology of the research on the precast assembly shear wall structure is the connection of joints.The joints of the precast assembly concrete shear wall structure mainly through the interface bond,the bond between grout and concrete,the connecting bars to achieve the transfer of force.It is of great importance to study on the joints of the assembly shear wall structure.The shale ceramsite concrete is a new type of building material,which has many advantages like light weight,great seismic performance,good thermal insulation performance and so on.The shale ceramsite concrete has been widely used in cast-in-situ concrete structure,however,the application in precast assembly shear wall structure is still rare in China,the reason is the lack of relevant research,and a series of technical problems have not been effectively resolved.The research and application of lightweight aggregate concrete represented by shale ceramsite concrete in assembly structure is still rare in Hubei province or even the whole country.The combination of shale ceramsite concrete and assembly structure for the efficient and energy saving mode of production is like adding a beautiful thing to a contrasting beautiful thing,further expands the advantages of precast concrete shear wall structure in the field of green building,and is line with the inevitable trend of the development of the construction industry in Hubei province,to this end,the relevant research work also need to follow up in a time.The study in this paper mainly focuses on the bond slip behavior of the filling hole for grouting steel bar in the application of shale aggregate concrete in precast assembly shear wall structure,and the specific research contents include the following:(1)The author adopts connection form of the filling hole for grouting steel bar of precast shale ceramsite concrete.The test have made 12 beam specimens and 2 cast-in-situ concrete beam specimens which considering three factors: bar diameter,spiral hoops ratio and the shale ceramsite concrete strength with the bond slip behavior,and the test have been carried out.(2)From the analysis of the bond slip curve obtained by the beam test,it shows that with the increase of slip,the bond stress increases first and then stay stable.The beam test specimens show obviously linear features in the elastic stage,and the specimens are all shown to yield in the end,no splitting failure or failure of the reinforcement is occur.(3)According to the experiment data,we can get the ultimate bond strength of each beam specimens with the load value,the strain value of steel bar and the slip value.and put forward the recommendation of the ultimate bond strength formula which applied to the shale ceramsite concrete filling hole for grouting steel bar through theoretical simulation.(4)An optimum curve of the corresponding bond stress and slip at all levels of the load by least square method has been fitted out on the basis of the beam test date.Considering the influence of three factors comprehensively,an expression of bond-slip is established which is suitable for the shale ceramsite concrete filling hole for grouting steel bars.The expression form is simple which can provide theoretical basis and design recommendation for building a meticulous finite element beam model.