Research On Safety Performance Of Sleeve Grouting Splice Under Vibration Load And Freeze-thaw Cycle

In recent years,China has vigorously developed assembly building.The key to ensure the safety and stability of assembled buildings is the performance of connection nodes between prefabricated components.Nowadays,sleeve grouting connection is widely used.Through a large number of engineering examples and test tests,grouting splices are constructed in ideal environment,and the mechanical properties of the splices can meet the requirements of specifications.But in the actual construction process,it will inevitably be affected by some external environmental conditions.For example,in the process of building assembled buildings on the existing subway lines,the vibration load caused by vehicle operation will affect the sleeve grouting material,which is subjected to vibration load in the solidification process,and will inevitably affect the mechanical properties of the grouting splices eventually formed to a certain extent.At the same time,as one of the most widely distributed countries in the cold regions of the world,sleeve grouting connections will inevitably be affected by freeze-thaw cycles.At present,there are few studies on these two factors,so this paper takes GT4 semi-sleeve grouting splice as the research object,and analyses the mechanical properties of sleeve grouting splice specimens under the above two special conditions.The main research contents and achievements are as follows:1)Taking the vibration load and freeze-thaw cycle conditions as the influencing factors,GT4 semi-sleeve grouting splice as the research object,combined with actual engineering conditions,a reasonable and feasible indoor test scheme was formulated and tested.2)The sleeve grouting splice specimens consisting of CGMJM-VI high strength cement grouting material with designed compressive strength of 85 MPa,GT4 semi-grouting sleeve of steel bar and HRB400 grade steel bar with diameter of 14 mm and 20 mm,after being subjected to vibration loads with amplitude of 0.1-1mm and frequency of 0.5-2Hz,its mechanical properties can meet the requirements of the code.The sleeve grouting splice can be used in the construction of assembled buildings under the above vibration loads.3)The increase of amplitude in vibration load will reduce the ultimate bearing capacity of sleeve grouting splice specimens,and at the same time,the increase of amplitude in a certain range will have a negative impact on the anchorage performance between reinforcement bar and grouting material in sleeve,and after that,it will have a beneficial impact.The critical size of specific range needs to be further studied in the follow-up test.Frequency variation in vibration load has little effect on mechanical properties of sleeve grouting splice.The effect of the eccentricity of reinforcing bar caused by vibration load on the mechanical properties of splice specimens is very small.4)The sleeve grouting splice specimens consisting of CGMJM-VI high strength cement grouting material with designed compressive strength of 85 MPa,GT4 semi-grouting sleeve of steel bar and HRB400 grade steel bar with diameter of 14 mm and 20 mm,after the freeze-thaw cycles at temperatures ranging from-15~6?,the mechanical properties still meet the requirements of the specifications.But the ultimate bearing capacity,failure displacement and other data performance indicators have declined to a certain extent,and the decline increases with the increase of freeze-thaw cycles.