DAMAGE AND PLASTICITY IN MICROPLANE THEORY

The paper deals with the microplane model, in which the stress-strain relations are defined independently on planes of all possible orientat ions in the microstructure, and the microplane stresses or strains are then constrained kinematically or statically to the macroscopic stres s or strain tenser. The existing formulations of the microplane consti tutive model for concrete are mainly based on the kinematic constraint . They have been shown capable of reproducing satisfactorily most expe rimental results available for concrete specimens, with the advantages of great conceptual simplicity, convenient numerical explicitness, in trinsic induced anisotropy and microcrack opening-closure conditions, etc. However, from the theoretical viewpoint little has been said abou t how these formulations relate to classical constitutive models of el asto-plasticity or continuum damage mechanics. In this paper, a new ap ercu of microplane theory is achieved by systematically introducing da mage and plasticity concepts into the microplane framework. New insigh t is provided on the role played by the split of the normal components , and on the role of the different possible types of micro-macro const raint. Specific formulations are developed and discussed within the ne w theoretical framework, which can be easily related to von Mises plas ticity and to the existing models based on the second and fourth-order damage tensors. (C) 1997 Elsevier Science Ltd.