COMBINED PLASTICITY AND DAMAGE MECHANICS MODEL FOR PLAIN CONCRETE

A combined plasticity and damage mechanics model for concrete is developed within the general framework of the internal variable theory of thermodynamics. The necessity of using both plasticity and damage mechanics is discussed and the corresponding surfaces are developed via the internal dissipation inequality. The damage surface is a consequence of a damage evolution law based on the physical aspects associated with two modes of cracking. Both hardening and softening features are displayed by the damage surface. The plasticity surface is the classical one of von Mises with strain hardening but not strain softening. The combined theory is capable of accommodating the anisotropy induced by microcracking and is very suitable for computer implementation. The simultaneous use of the damage surface, which is pressure dependent, and the plasticity surface, which is chosen here to be pressure insensitive, leads to a constitutive model that displays the essential features of concrete inelasticity. These features, which include dilatation with shear and enhanced ductility with increased values of mean pressure, are shown together with comparisons of theoretical and experimental data. © ASCE.