A constitutive law with improved continuous-discontinuous description of fracture in concrete

Abstract

Paper presents an improved version of the constitutive model which combines a continuous and discontinuous crack’s description to simulate the concrete under tensile dominated loads. In a continuum regime, a plasticity model with a Rankine failure criterion and an associated flow rule was used. To describe the width of strain localization and to obtain mesh-independent results, the continuum constitutive law was equipped with a characteristic length of micro-structure by applying a non-local theory in an integral format. For describing displacement jumps along/across cracks, the eXtended Finite Element Method (XFEM) was used. A transition algorithm between a non-local continuum model and XFEM was formulated. A transfer function was introduced to enable a gradual switch from a continuous (smeared) to discontinuous (discrete) softening process. Several benchmarks were numerically simulated with a dominated mode-I (e.g. uniaxial tension and bending) and under mixed-mode conditions.