Study On The Mechanical Behavior Of Steel Sleeve Grouting Connection

The prefabricated concrete building structure is advantageous for large-scale production,fast construction,short construction time,material saving,and provides superior innate conditions for vigorously developing the assembled building structure.Coupled with the advancement of society and technology,and the acceleration of urbanization,the prefabricated concrete building structure has received more and more attention.The steel sleeve grouting connection technology is the key technology for the prefabricated steel bar connection,which can ensure the reliability and integrity of the structure.Based on the summary of the research and application status of grouting sleeve connection technology at home and abroad,a new type of surfacing welding grouting sleeve is proposed.The sleeve is made of high quality seamless steel tube as the material,and the inner wall of the sleeve is welded to form a hoop convex.Ribs can effectively increase the mechanical bite force of the sleeve and the grout.Compared with the existing ductile iron sleeve and chip processing sleeve,the utility model has the advantages of simple production process and low cost.The uniaxial tensile performance test of the new surfacing grouting sleeve under the influence of five factors of grouting compressive strength,sleeve outer diameter,ring rib spacing,anchoring length and number of ribs was earried out on 33 specimens.The main contents of the study are the failure mode of the test piece,the ultimate bearing capacity of the test piece,the optimal sleeve form,the load-displacement curve,the load-strain curve and the strain distribution on the steel bar and the sleeve surface.The research shows that:(1)There are two modes of steel bar unloading failure and bond-slip failure.(2)Through the analysis of the test pieces of Group A,it can be concluded that the ultimate bearing capacity increases with the increase of the anchor length when the steel bar is pulled out.When the steel bar is broken,the ultimate bearing capacity is not affected.(3)Through the comparative analysis of the test pieces of Group A and Group B,it can be concluded that the reduction of the number of ribs has no effect on the ultimate bearing capacity of the test piece.(4)Through the comparative analysis of the test pieces of group A,group C and group D,it can be concluded that when the steel bar 1s pulled out,compared with the group A,the ultimate bearing capacity increases with the increase or decrease of the ring rib spacing.When the steel bar is broken,the ultimate bearing capacity is not affected.As the spacing of the ring ribs increases,the anchor length of the steel bar is increased.(5)Through the comparison of the failure modes of the above-mentioned test pieces and the test pieces of Group A,Group E and Group F,the conclusion can be drawn:when the steel bar is pulled out,the outer diameter of the sleeve is increased and decreased compared with the group A,and the ultimate bearing capacity is obtained.Both are improved.When the steel bar is broken,the ultimate bearing capacity is not affected.As the outer diameter of the sleeve increases,the anchor length at which the steel bar is broken is reduced.(6)Through the comparison of the failure modes of the above figure and the A,G and H specimens,it can be concluded that the ultimate bearing capacity increases with the increase of the grouting.strength when the steel bars are pulled' out.When the steel bar is broken,the ultimate bearing capacity is not affected.As the strength of the grout increases,the anchor length of the steel bar is reduced.(7)The diameter of the steel bar is 25mm,the model is HRB400.The optimal sleeve form is grouting strength of 95.3MPa,sleeve outer diameter is 57mm,ring rib spacing is 25mm,anchoring length is 6d,ring rib number is 5.