Plasticity model for directional nonlocality by tension cracks in concrete planar members

The concept of directional nonlocality is defined to describe the inherent characteristics of concrete tensile cracks affecting the compressive behavior as well as the tensile behavior of concrete. In the cracked concrete, the crack damage in one direction is influenced by damages from other directions. In the present study, a material model was developed to describe the directional nonlocal effect by tension cracks in concrete planar members. For nonlinear numerical analysis of concrete, the proposed directionality parameter was employed in the plasticity model with multiple failure criteria, and an identical tension crack parameter was used for both the tensile behavior and compressive behavior of the concrete. In the proposed plasticity model, tensile and compressive micro failure surfaces defined in the prescribed multiple fixed orientations were used to describe the directional nonlocality in the micro-structure of concrete, and the overall failure surface of the concrete was calculated by averaging the multi-oriented micro-surfaces. The proposed plasticity model was used for nonlinear finite element analysis of reinforced concrete shear panels, and the analysis results were compared with test results.