A comparative study of isotropic and anisotropic descriptions of damage in concrete structures

Abstract

Scalar damage models are very often implemented in computational analyses in order to predict the responses and failure modes of concrete and reinforced concrete structures. In most situations, however, damage is not isotropic but rather geometrically oriented. Therefore, there as been many questions about the pertinence and range of applicability of isotropic, scalar, damage models for describing a degradation process which is strongly geometrically oriented. In order to assess what are the limitations of such a simplifying assumption, a comparative study is presented. The scalar damage model is compared with another model where damage induced orthotropy is taken into account. Structural analyses on bending beams, compression-shear and tension-shear concrete panels are discussed. Although it may appear to be simplistic, the scalar damage model provides accurate predictions when failure is due to uniaxial extension. Crack closure introduces an additional anisotropy which is important in compression-shear problems. Finally, damage induced anisotropy seems important when failure is due to multiaxial extension, such as in sheartension problems.