Microscale Fracture Damage Analysis of Lightweight Aggregate Concrete under Tension and Compression Based on Cohesive Zone Model

AbstractThe secondary pre-processing development of Abaqus based on the Python program is carried out, and the mesoscale finite-element model of light-aggregate concrete is established at mesoscale. A Python program capable of batch insertion of cohesive elements is also developed to simulate discrete crack initiation and propagation behavior inside multiphase mesoscale heterogeneous structures. The whole mesoscale deformation process of light aggregate concrete is simulated under both uniaxial tension and uniaxial compression. A parametric study on fracture energy, mixed fracture energy ratio, cohesive stiffness, and shear strength of each mesoscale component is conducted. The influence of mesoscale fractures on the overall mechanical properties of light-aggregate concrete is investigated from the perspective of damage morphology and mechanical response. The results show that the mesoscale light-aggregate concrete model can effectively simulate the fracture damage process of light-aggregate concrete under uniaxial tension and compression by comparison with experiments. The increase of mixed fracture energy ratio can significantly enhance the deformation of light-aggregate concrete in the softening section, and the degradation of residual strength becomes slower. The increase of cohesive element stiffness of each mesoscale component of light-aggregate concrete decreases the peak tensile strain and peak compressive strain of light-aggregate concrete under uniaxial tension and compression. It enhances the elastic modulus of light-aggregate concrete. Among the mesoscale components of light-aggregate concrete, the compressive strength of light-aggregate concrete under uniaxial compression is most sensitive to the change of the ratio of shear strength to the tensile strength of mortar, the second is aggregate, and the interface transition zone is weakest.