Comparative Analysis And Optimal Design Of Mechanical Performance Test Of Various Grouting Sleeve

With the rapid development of prefabricated buildings,the research and application of prefabricated buildings in my country have entered a critical development stage.The mechanical performance of the grouting sleeve connection between prefabricated components directly affects the safety and durability of the structure.Due to improper operation of the components during transportation or assembly,the bending of the embedded steel bars often occurs.Even after straightening,the effective anchorage length of the embedded steel bars will be reduced,or the anchorage length of the steel bars will be insufficient due to grouting dissatisfaction It often happens that the pre-buried steel bars are uneven.At present,the types and construction types of grouting sleeves in the domestic market are different,and the sleeves used in actual projects are uneven.The above factors may affect the performance of the grouting sleeve connection.In addition,domestic experts and scholars have done very little lateral comparison research on the mechanical properties of different grouting sleeves.Therefore,in order to further study the mechanical performance of the grouting sleeve connection,this paper through the investigation of nearly 20 domestic grouting sleeve manufacturers,combined with the problems of the sleeve connection in practical engineering applications,choose three with more dosage and different construction forms A variety of mainstream grouting sleeves(casting full grouting sleeves,casting semi-grouting sleeves and mechanically processed full grouting sleeves)are the main subjects of research.First,the uniaxial tensile test was used to study the three types of grouting sleeve joints of different construction forms under different anchorage lengths of steel bars(8d,6.5d,6d,5.5d)and steel bars 8d completely deviated from the wall.And the effects of destruction.Then,based on the existing experiments,the modeling methods that are effectively applicable to the three grouting sleeve connection joints are proposed,and the applicability of the modeling methods is verified.Finally,the stress analysis and optimization of the sleeve were carried out based on the reason why a large number of steel bars were bonded and slipped during the machining of the fully grouted sleeve joint.The main findings are as follows:(1)The influence of the anchoring length on the mechanical properties of the three grouting sleeves can be found: the two casting sleeve joints are within the 8d-5.5d anchoring length,and the uniaxial tensile bearing capacity of the sleeve joints is not much different and both Class I joint strength requirements.The reduction in anchoring length has little effect on the ultimate bearing capacity of the two casting sleeve joints under uniaxial tension.Mechanically processed full grouting sleeve is within 8d-5.5d anchoring length,50% of the joints have fracture and failure of the reinforcement outside the sleeve,the bearing capacity meets the strength requirements of Class I joints under static load,and 50% of the joints have steel bar slippage and damage Although the force meets the strength requirements of Class I joints under static load,its axial deformation is large,and the joint safety assurance rate is low.Under uniaxial tension,the safety reserve of the machined sleeve joint is lower than that of the two cast sleeve joints.(2)Regarding the influence of the partial wall of the steel bar on the mechanical properties of the three grouting sleeves,it can be found that the joints of the two cast sleeve joints are all the fracture and failure of the outer steel bar when the 8d steel bar is completely partial,and the bearing capacity is not much different And meet the strength requirements of Class I joints,the partial wall of the steel bar has little effect on the uniaxial tensile bearing capacity of these two sleeves.In the case of mechanically processed sleeve joints,when the 8d steel bar is completely deviated from the wall,one joint occurs steel bar slip damage,and the axial deformation is too large,and the joint safety performance is poor.Under uniaxial tension,the safety reserves of the two cast sleeve joints are better than the machined sleeve joints.(3)On the basis of the existing experiments,this paper proposes a modeling method that is effectively applicable to the three grouting sleeve connection joints,proves the effectiveness and applicability of the finite element simulation method,and lays a foundation for optimization analysis.(4)The simulation results show that,without changing the grouting strength,sleeve strength,sleeve length,etc.,the sleeve can increase the ring ribs reasonably,which can effectively enhance the bonding force between the steel bar and the grout in the anchoring section The safety guarantee rate of steel bar bond slippage damage.