Fracture Mechanics Analysis Of CFRP Reinforced Concrete Beams With Cracks

Recently, CFRP(Carbon Fiber Reinforced Polymer) has been wildly applied in reinforcement. Many researchers did lots of studies in normal performance of CFRP reinforced concrete structures or members, and achieved many results. This paper attempts to base on concrete fracture mechanics and anisotropic elasticity theory, and research fracture properties of crack in reinforced concrete beams and strengthened with CFRP plates after crack in reinforced concrete beams respectively by ANSYS finite element numerical simulation method.This paper uses the example of CFRP reinforcement containing cross straight through the cracks of reinforced concrete beams and reinforced concrete beams penetrate oblique crack. By using ANSYS finite element numerical simulation method, this paper calculates the crack-tip stress intensity factor K value before and after the reinforcement. And also compares fracture resistance of reinforced concrete beams before and after the CFRP reinforcement, discusses the impact CFRP sheet length, thickness, and material changes in the stress intensity factor. After that, this paper uses the example of CFRP reinforced concrete beams bonding interface crack, studies the interfacial crack from a macro point of view of fracture mechanics and uses finite element simulation to calculate the end of the crack tip stress intensity factor K value, discusses the impact CFRP sheet length, thickness, and material changes in the crack tip stress intensity factor.The results show that using CFRP reinforced concrete beams can significantly improve fracture resistance. After the crack tip stress intensity factor reinforcement of concrete beams reinforced significantly reduced compared with that before, but increasing the stiffness of the beam is not obvious. The crack tip stress intensity factor has a certain impact by reinforcement sheet length or thickness variation. In most cases, with the increase in the number of layers and the length of the reinforcing sheet, the crack tip stress intensity factor decreasing trend.It shows that 6K carbon fiber sheet is better than other materials in reinforcement effect by changing the materials of FRP, but the structure changes of CFRP sheet does little effect on the fracture resistance of concrete beams.