Experiment And Analysis Of Mechanical Properties Of 28mm High-strength Steel Bar Sleeve Grouting Connection

With the continuous improvement of the demand for seismic capacity of buildings and the renewal of the society’s awareness of the concept of green environmental protection,600 MPa steel bars are used in high-rise buildings because of their advantages such as high strength,good plasticity,material saving,and environmental protection.Come higher.In response to the concept of low-carbon development of modern industry in the "14th Five-Year Plan",this paper carried out high stress repeated tests on the reinforced sleeve grouting connection joint specimens made of 28 mm HRB600 E steel bars,high-strength cement-based grouting materials and GDPS deformed sleeves.20 times of cyclic load test of tension and compression,8 times of repeated tension and compression of large deformation,and uniaxial tensile test were carried out to study and analyze its mechanical properties,and use ANSYS software to carry out finite element simulation of joint specimens.The main research contents and achievements are as follows:（1）39 specimens of steel bar sleeve grouting connection joints were produced in the test,3 joint specimens were subjected to 8 cyclic load tests of repeated tension and compression with large deformation,and 3 joint specimens were subjected to 20 cyclic load tests of repeated tension and compression of high stress.There are 7 pieces and 29 joint pieces for uniaxial tensile test.There are four kinds of failure phenomena in the test: the pull-out failure of the steel bar at the grouting port,the pull-out failure of the steel bar at the grouting port,the pull-off failure of the steel bar at the grouting port and the pull-out failure of the steel bar at the grout port.（2）Using the length of the steel bar embedded in the sleeve cavity,the number of ring ribs on each side of the sleeve,and the strength of the grouting material as the parameter variables,the influence of the parameter variables on the residual deformation and ultimate load of the specimen is studied.The research results show that when the length of the steel bar embedded in the sleeve cavity reaches 8d,the influence of the increase of the ultimate load of the butt joint specimen with the length of the steel bar embedded in the sleeve cavity gradually decreases,but it increases with the increase of the strength of the grouting material;the residual deformation is affected by the effect of grout strength is small;bearing capacity increases as grout strength increases.（3）Analyzing the test results and ANSYS numerical simulation results,the stress distribution law on the surface of the cylinder wall is obtained: the outer surface of the smooth section of the sleeve cylinder wall shows tensile stress,and the tensile stress gradually decreases from the middle to the two ends;the deformation section at both ends of the sleeve Expressed as compressive stress,the compressive stress between the innermost ring rib and the inner second ring rib is the largest,and the compressive stress gradually decreases from the inner side of the sleeve to both ends.（4）From the test results and ANSYS simulation results,the load-strain relationship curve of the sleeve wall is extracted,and it is concluded that the axial and hoop strains on the surface of the cylindrical rib in the deformation section of the sleeve are both compressive strains,and the innermost two annular rib The strain between the ring ribs is the largest,and both the tensile strain and the compressive strain exist between the ring rib and the ring rib.The axial strain of the smooth section is all tensile strain,and the strain value of the smooth section is larger than that of the deformed section.（5）The ultimate load,yield load,stress and strain distribution of the sleeve surface of the specimen are output from the ANSYS finite element simulation results.The finite element simulation results and the test results are compared and analyzed,and the strain distribution law of the sleeve surface is obtained.For HRB600 E steel bars with a diameter of 28 mm,the outer diameter of the GDPS sleeve should reach 68 mm,the wall thickness should be 5.5 mm,6 ring ribs should be set at the deformation sections at both ends of the sleeve,and the length of the connecting steel bars embedded in the inner cavity of the sleeve should reach 8d.