A Third‐Invariant Plasticity Theory for Low‐Strength Concrete

Abstract

A theory of plasticity for frictional materials is developed in which first and third invariants of stress and strain are used instead of the more conventional second invariants. The usual concepts of strain‐hardening plasticity are used with the exception that a nonassociated flow rule is required to control dilatation. A procedure for determining material parameters is outlined. For a weak concrete, detailed comparisons are made between theoretical and experimental stress‐strain data for a large number of three‐dimensional paths.