Of Cfrp Tendons Mounted To Reinforced Concrete Tension Members Interfacial Mechanical Properties Of Finite Element Analysis

In the past two decades, the fiber-reinforced plastic/polymer, with the advantages of light-weight, high-strength, corrosion resistance and fatigue resistibility, has been broadly used in structural strengthening. As a new technique, near surface mounted (NSM) FRP reinforcement has been used in concrete structure recent years. Because of more virtues than traditional strengthening techniques, the method of NSM should be broadly used in the field of engineering reinforcement.In this paper, the bond interface mechanical behavior of concrete tension members strengthened with near surface mounted CFRP rods has been investigated. Under applied force, because of the different material properties of CFRP rod, binder and concrete, the interfaces between different materials are the weakness. Compared with the bond mechanism of concrete members strengthened with FRP rods and concrete members strengthened with surface bonded FRP laminates, two kinds of bond failure at the interface, that is the interface between CFRP rod and binder, binder and concrete, is analyzed, and the bond mechanism at the interface is simulated by the relationship between bond shear stress and slip.Based on the theory nonlinear finite element and the mathematical model of the relationship between bond shear stress and slip, the finite element models of concrete tension specimen near surface mounted CFRP rod, of which the dimension of trough mounted are different, have been set by the finite-element software of ANSYS. This finite element model is used to analyze two kinds of bond failure at the interface. In the finite element model, concrete and epoxy binder have been simulated by using Solid65 element, CFRP rod has been simulated by using Pipe20 element, and the bond failure interface has been simulated by using Combine39 element. Based on the results of the finite analysis, the relationship between bond shear stress and slip of the interface between epoxy and concrete is improved.Finally, the longitudinal mechanical behavior of the bond failure interface is researched based on the element force of element Combine39 in the finite model, which is set at the bond failure interface longitudinally, and the distribution of shear stress of interface along the embedded length is obtained. According to the distribution of shear stress of interface along the embedded length, when bonding interface damages, the anchorage length of reinforcement concrete member near surface mounted CFRP rod under applied tension is defined. By the numerical means, the anchorage length of concrete tension members strengthened with near surface mounted CFRP rods under applied force is solved, by using the relationship between bond shear stress and slip, accordingly to different kinds of failure at the interface.