This research pertains to expand the formulation and applicability of using confinement and expansion due to Poisson’s ratio models for three dimensional non-linear finite element analysis of reinforced concrete members. A plasticity based model that acknowledges the asymmetric response of reinforced concrete under multiaxial stress conditions is used to account for the strength improvement under conditions of triaxial compression. Complex behavior of concrete such as compression softening and tension softening are incorporated to simulate concrete behavior. DIANA software is used for finite element analysis with the inclusion of confinement and
expansion effects. The concept of material pre-strains is extended to accommodate modeling of the Poison’s ratio effect. The applicability of the suggested confinement and expansion models are verified by comparing the results of Kupfer and Vecchio – Collins tests on shear panels with that obtained from DIANA software. These comparisons illustrate the ability of the confinement and
expansion models to obtain the response of reinforced concrete members subjected to multiaxial stress conditions.