Research On Joint Detection And Mechanical Properties Of Fabricated Concrete Structure

With the development of domestic economy and the reform and upgrading of construction industry,the disadvantages of traditional construction are increasingly prominent.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.There are a large number of connection nodes in the prefabricated concrete structure,and the nodes are mostly connected by steel grouting sleeves.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,based on the method of nondestructive testing,the quality of the horizontal joint is explored,and the connection mechanism of the sleeve are numerically analyzed.The main results are as follows:The grouting material is the key material for the reinforcement grouting connection and must meet certain requirements.Based on the experimental specifications,the basic performances of two grouting materials,such as strength,fluidity and setting time,are analyzed,and selects the grouting material that meets the requirements.The sound velocity of the grouting material at different age is tested,and the relationship between the sound velocity and the strength is also analyzed.The results show the strength of grouting material grows faster in the early stage and tends to be stable after 7 days.With the increase of age and intensity,the sound velocity value of the grouting material also becomes larger,and tends to be stable after 28 days.Detection of assembly column using ultrasonic head wave time method.Based on the sound speed,amplitude and waveform recorded by the ultrasonic tester,the qualitative judgment is made as to whether or not there are defects inside the fabricated structure.It is analyzed that the ultrasonic wave can distort when the cavity is void in the joint.Based on the analysis of the test data,a model for predicting the size of the cavity defects is established through the study of the ultrasonic propagation path.The test results show that the first wave acoustic method is feasible and adaptable,and the model has a more accurate estimation accuracy.ANSYS software was used to numerically simulate the force transverse process of steel grouted sleeve connection.Under one-way repeated tension and compression,the stress-strain distribution law of the joint was obtained,and the residual strain after unloading of rebar,grouting material and sleeve was obtained,and also obtained the Mises stress distribution and stress concentration.The contact stress distribution of reinforcing steel bar grouting material and grouting material sleeve two contact surface is analyzed,and the location of contact pressure on contact surface is explored.Finally,it is found that the contact pressure of ribs and sleeve shear grooves is large,and the normal operation of ribs and shear grooves is an important guarantee for grouting connection.