Isotropic and anisotropic damage formulations for concrete fracture are re- viewed, including the classical fixed and rotating smeared crack models and more refined approaches based on the microplane concept. Higher- order gradients are introduced to avoid the boundary value problem…
Isotropic and anisotropic damage formulations for concrete fracture are re- viewed, including the classical fixed and rotating smeared crack models and more refined approaches based on the microplane concept. Higher- order gradients are introduced to avoid the boundary value problem be- coming ill-posed at the onset of softening. For an infinite one-dimensional bar dispersion analyses are carried out to examine the effect of using gra- dients of different strain measures or internal variables.