Study On Bond Anchorage Performance Of UHPC Anchorage Joint

Ultra high performance concrete(UHPC)as an advanced new material used in new fabricated structure will have the outstanding advantages of high strength,small self weight,good construction performance,high durability,large design freedom and so on.With the deep integration of new materials and new structures,considering the problems of large amount of waste concrete and low reuse rate caused by house demolition,recycled concrete is applied to solve the current situation of resource shortage and environmental deterioration,and the construction waste is recycled.Therefore,the bond performance of a new type of ultra-high performance concrete anchorage joint is studied,taking advantage of the good mechanical properties of UHPC,the good interface performance with normal concrete(NC)and the good binding force to reinforcement,the anchoring length is reduced and the amount of reinforcement and UHPC is saved by using the form of UHPC wrapped reinforcement,It solves the problem of high cost when ultra-high performance concrete is used in engineering,at the same time,it solves the problem of steel bar anchorage at the prefabricated joints,and the application of recycled concrete is of great significance to alleviate the current situation of resource shortage and environmental deterioration.First of all,test the mechanical properties of the test material,namely the cubic compressive strength test of ordinary concrete,recycled concrete and ultra-high performance concrete,the cubic split tensile strength test and the cylindrical axial compressive test;The recycled concrete with the same strength as C40 ordinary concrete is designed.Then,19 groups of 57 ordinary concrete-wrapped UHPC anchorage joint center drawing specimens were studied and tested.The influences of the thickness of UHPC,the surface treatment of concrete contact layer,the bond length and the diameter of steel bar on the bond performance of the anchorage joint are analyzed.The failure mode and bond slip curve of the specimen are analyzed,and the influencing factors are fitted by formulas respectively.The influence rules of various parameters on the bond anchorage performance of the specimen are obtained,and the anchorage form of the anchorage joint is proposed.At the same time,compare the anchorage joint with the same strength recycled concrete and ordinary concrete to obtain the test data and analyze the test phenomenon.Finally,the prediction formula of bond strength fitted by predecessors is summarized,the failure forms are classified,and the fitting parameters are determined by combining with the four influencing factors in the previous paper.The calculation formula of the ultimate bond strength of the new type of anchorage joint is fitted,and the formula of the critical bond anchorage length is obtained by comparing the experimental value with the theoretical value.