FAILURE PREDICTION OF SMEARED-CRACK FORMULATIONS

The smeared-crack approach of strain-softening is a popular engineerin g concept for the numerical simulation of tensile failure processes in concrete and rock. Despite numerous publications on the equivalent co nstitutive formulation of cracked solids, very little is known about t he predictive value of the smeared-crack approach, particularly when n onproportional load histories are considered. To this end, two failure indicators are examined at the constitutive level in order to assess the predicted failure mode of fixed and rotating crack concepts. The d irectional stiffness parameter is used to examine singularities of sme ared-crack formulations, which signal continuous failure due to materi al branching. In contrast, the localization indicator is used to exami ne the formation of weak discontinuities, which precede incipient fail ure process when the continuum degrades into a discontinuum. In this p aper both failure indicators will be used to assess the failure modes of the fixed and rotating crack formulations for two loading scenarios involving pure shear and combined tension with sheer.