Mode I crack propagation criterion of concrete and numerical simulation on complete process of cracking

A crack propagation criterion is proposed by utilizing the initial fracture toughness K~(ini)_(IC) as the material parameter.Once the difference between the stress intensity factor caused by the applied load and the stress intensity factor caused by the cohesive force reach the initial fracture toughness,the crack begins to propagate.Based on this method,the FEM is used to simulate the Mode Ⅰ crack propagation in concrete.For the specimens with different sizes,the complete P-CMOD curve,the pre-critical crack propagation length Δa_c and the unstable fracture toughness K~(un)_(IC) of concrete are obtained respectively.The simulation is in good agreement with experimental data and the computational results using DIANA.It is concluded that if the elastic modulus E,the uniaxial tensile strength f_t and the initial fracture toughness K~(ini)_(IC) of concrete are measured,the unstable fracture toughness K~(un)_(IC) and the complete process of crack propagation can be obtained by using the proposed method.