Study On The Connection Performance Of Pre-grouting Sleeve Steel Bar

With the continuous advancement of building industrialization,the connection technology of assembled concrete structure is constantly updated.In the past,the disadvantages of the traditional grouting sleeve steel bar connection technology are increasingly exposed,which will not only produce the technical problem of grouting,but also increase the amount of steel used for making grouting mouth and slurry discharge mouth.Therefore,aiming at the problem that the connection quality is not easy to guarantee in the traditional grouting sleeve connection method,combined with the current grouting sleeve connection method,this paper cancels the grouting mouth and slurry discharge mouth of the cylinder body on the basis of the traditional grouting sleeve,and puts forward the method of normal grouting sleeve reinforcement connection method.The specific connection method is as follows: the opening end of the semi-grouting sleeve is used up,and the grouting hole on the side is cancelled.The grouting material is first poured into the top,and then the steel bar is inserted to complete the steel bar connection.After searching,no literature on this connection method was found.Therefore,through the combination of experimental research and numerical simulation,this paper studies the reliability of steel bar connection under various tolerance conditions in actual construction,and lays a foundation for the promotion and application of this connection method.The research contents of this paper mainly include:(1)In order to obtain the basic performance parameters of the material,the mechanical properties of the main materials such as steel bar and grouting material used in the connection test of the positive pre-grouting sleeve are tested.(2)In order to simulate the actual situation that the upper steel bar may not be completely inserted into the bottom of the sleeve due to the errors caused by various possible factors under the actual working conditions,considering the three bias states of centering,eccentricity and inclination,the steel bar is inserted into the sleeve in each state.After that,five heights of 0 mm,5 mm,10 mm,15 mm and 20 mm are raised respectively due to the adjustment of prefabricated components,forming 3 × 5= 15 working conditions.HRB400 steel bars with two diameters of 12 mm and 16 mm and the corresponding grouting sleeve are used.Three test specimens are made for the diameter of the steel bar corresponding to each working condition.A total of 3× 15 × 2 = 90 normal first grouting sleeve steel bar connection test specimens were made.(3)Uniaxial tensile tests were carried out on the test specimens of positive pre-grouting sleeve steel bar connection on the universal testing machine.According to the test results,the failure state,ultimate bearing capacity and load-displacement curve trend of the test specimens were compared,so as to analyze the influence of various factors such as steel bar offset state and steel bar anchorage length on the connection specimens of two steel bar diameter types,and further study the effectiveness of positive pre-grouting sleeve steel bar connection.(4)The finite element simulation software ABAQUS was used to establish and calculate the solid model of 30 groups of normal grouting sleeve reinforcement connection test specimens with different parameters.Combined with the test results,in the numerical simulation,the steel bar,grouting material and sleeve are fixedly connected,and the mechanical performance of the steel bar connection of the positive first grouting sleeve is explored by the numerical simulation method.The test results were compared with the numerical simulation results,and the load-displacement curves of 12 mm and 16 mm diameter specimens were drawn to compare the conformity of the two.Provide technical support for the application.