Study On Mechanical Properties Of New Corrugated Grouting Sleeve For Steel Bar Connection

Prefabricated buildings have shown a rapid growth trend in my country in recent years.Compared with traditional cast-in-place structures,prefabricated concrete structures have got rid of the dependence on a large amount of labor.At the same time,standardized factory operations can ensure the quality of components,reduce material waste,and reduce the environment.Pollution.The most widely used connection technology for prefabricated concrete buildings is the grouting sleeve grouting steel connection technology.The grouting sleeve is a key component of the connection technology.Its mechanical properties and deformation performance play a vital role in the reliability and connection of the connection.At the same time,the economical grouting sleeve is effective in reducing the cost of prefabricated concrete structures.Vital meaning.This paper proposes a new type of corrugated grouting sleeve,which is made of seamless steel pipes by rolling processing.It has the characteristics of sufficient raw materials,easy processing,and good economy.This paper will systematically compare the relevant mechanical tests with simulation analysis.The force performance of the sleeve is studied,and the main research contents are as follows:(1)In this paper,45 new corrugated grouting sleeve steel connection joints are tested for the reliability of steel joints.All joint specimens are steel fracture failure.The ultimate bearing capacity,elongation and residual deformation of the joints are included in the specifications and specifications.Comparing with the standard,except for the eccentric test piece,the other test pieces meet the mechanical and deformation performance requirements of Class I joints,indicating that the new corrugated grouting sleeve grouting connection joint has excellent mechanical properties.(2)According to the axial and circumferential strain results of the joint sleeve surface,the corresponding strain results are analyzed and compared,and it is found that the maximum axial strain appears in the middle of the sleeve and gradually decreases to both sides.The maximum tensile strain in the hoop direction appears in the first depression of the corrugated structure at both ends of the sleeve,and the maximum compressive strain appears in the middle of the sleeve.The hoop tensile strain of the sleeve is caused by the corrugated section structure of the sleeve which makes the grout produce a "cone wedge" effect on the inner wall of the sleeve.This structure improves the mechanical bite force and bonding strength of the sleeve.Under repeated tension and compression,the compression stiffness of the joint is greater than the tension stiffness.The reason is that the grouting material has better compressive performance but weaker tensile performance,and the grouting material can participate in greater load sharing under pressure.(3)The initial restraint stress of the joint is calculated based on the thick-walled drum model,and a new method for calculating the ultimate bearing capacity of the corrugated grouting sleeve steel connection joint is proposed based on the previous research,which is compared with the test results.The calculation method of the bond strength of the steel bar and the calculation method of the ultimate bearing capacity of the joints proposed in this paper are more consistent with the test results,which can better predict the ultimate bearing performance of the new corrugated grouting sleeve,which has reference value for engineering applications.(4)The analysis of the strain law was further confirmed by the finite element analysis,which proved that there is an obvious "cone wedge" effect of the grouting material in the depression of the corrugated structure.Through the comparison and analysis of the simulation results,it is found that the joints formed by the sleeves with two corrugated structure sections arranged on both sides of the sleeve are more advantageous in the uniformity of the stress distribution and the ability to restrain the grouting material.It is recommended to install two corrugated structures.,The concave depth of the corrugated structure is preferably 2～5mm.