FE ANALYSIS OF STRAIN LOCALIZATION IN CONCRETE IN ELASTO-PLASTICITY AND DAMAGE MECHANICS WITH NON-LOCAL SOFTENING

Abstract

Results of Finite Element Method (FEM) simulations of a strain localization in concrete specimens are presented. Two different continuum approaches have been used to model to behaviour of concrete: (i) an elasto-plastic constitutive law with the Drucker Prager criterion in the compression regime and the Rankine criterion in the tensile regime, with isotropic hardening and softening and (ii) an isotropic continuum damage model with the equivalent strain corresponding to the Rankine failure criterion and modified Huber Mises criterion in terms of strains, with exponential softening. Both constitutive models were enriched by non-local terms to describe strain localization properly, ensure mesh-independence in the softening regime and capture the deterministic size effect. The constitutive models were used to simulate strain localization in concrete in two boundary value problems under plane strain conditions, viz. uniaxial tension and three-point bending. The effect of the characteristic length on load-displacement curves and widths of strain localization is discussed.