A method has been used to simulate shear failure in reinforced concrete elements considering localization phenomenon. This paper is dedicated to the modeling of the shear band localization in context of large strain accumulation in a narrow band without substantially affecting the strain in the surrounding material. This phenomenon frequently occurs accompanying inelastic deformation and material acoustic tensor looses its positive definiteness. Furthermore, finite element method is used to simulate this phenomenon. The model, when used in finite element context, gives mesh-insensitive results regarding to the width and direction of the shear band.

In this paper, a unified plastic model for concrete, in which only one criterion is considered to describe the behavior of concrete under different stress states, is used. This model can treat a major nonlinear phenomenon of concrete such as cracking; shear transfer degradation, tension stiffening and compressive strength reduction. The objective of this paper is to follow mentioned method together with presented formulation based on complementary matrix to analyze localized failure of RC panels as well as postpeak behavior while shear band is formed. This phenomenon occurs when the material acoustic tensor A(n) looses its positive definiteness and usually takes place when RC element fails in shear.