Study On Fracture Toughness Of Reinforced Concrete By Wedge Splitting Method

Reinforced concrete is widely used in civil engineering.Since concrete is a multi-component heterogeneous cement-based composite material,congenital internal defects such as voids and microcracks are inevitably generated during the production process.The failure of concrete structures is often related to the expansion of cracks.The introduction of steel bars has a certain inhibitory effect on the development of concrete cracks.The mechanical properties and structural stability of reinforced concrete structures have been improved.Therefore,it is of great significance to study the causes of cracks in reinforced concrete,predict the process of crack propagation,and study the fracture characteristics of crack propagation.In this paper,the fracture process of reinforced concrete and plain concrete is observed based on the electrical measurement method and the digital image correlation method(DIC method).The fracture characteristics of the specimen and the crack resistance of the steel bar are analyzed.The numerical simulation method is used to further explore the fracture process and characteristics of reinforced concrete.At the same time,the fracture process of reinforced concrete wedge splitting specimens was studied based on the analytical method and KR resistance curve.The research work of this paper includes the following contents:(1)The fracture process of specimens was monitored by electrical measurement and digital image correlation method,and the fracture characteristics of reinforced concrete and plain concrete were compared and analyzed.According to the load and crack tip opening displacement curve,fracture process zone and opening displacement curve obtained from the test,the influence of reinforcement on the bearing capacity of concrete wedge splitting specimens and the inhibition of crack development were analyzed.(2)The finite element analysis software ABAQUS is used to simulate the wedge splitting test of reinforced concrete.The simulation results are close to the experimental values to verify the reliability of the model.At the same time,the effects of reinforcement ratio,initial crack length and other parameters on the fracture properties of reinforced concrete were studied.(3)Based on the theory of fracture mechanics,the analytical method for the fracture process of reinforced concrete wedge splitting specimens is derived,and its applicability is verified by comparing with the experimental results.The fracture toughness of the specimen is solved by the law of fracture toughness parameters.At the same time,the influence of specimen size on the fracture characteristics and bearing capacity of reinforced concrete wedge splitting specimens was discussed based on the analytical method.(4)The crack propagation resistance curve(K_R resistance curve)of reinforced concrete wedge splitting specimens is obtained by calculating the stress intensity factor of the fracture process and using the superposition principle.The influence of parameters such as specimen size and steel bar position on K_R resistance is discussed.