Size Effect of Shear Fracture Energy of Concrete in Uniaxial Compression Based on Gradient-dependent Plasticity

摘要

Gradient-dependent plasticity where a characteristic length is involved into yield function is adopted to calculate the thickness of shear band (SB) and the distribution of plastic shear strain in SB. The characteristic length reflecting the heterogeneous extent of texture only controls SB's thickness. The local plastic shear strain in SB is highly non-uniform. The total fracture energy is the sum of pre-peak and post-peak fracture energies. The pre-peak part is described by the nonlinear Scott model and depends on the height of specimen. The post-peak part is calculated through the derived post-peak relative stress-plastic deformation curve. If the inclination angle of SB is not influenced by the height, then the slope of post-peak relative stress-plastic deformation curve and the post-peak fracture energy are independent of the height. The total fracture energy is linearly size-dependent as the pre-peak fracture energy is linearly related to the height. The slope of post-peak relative stress-plastic deformation and the total fracture energy are verified through previous experiments for normal concrete in uniaxial compression.