Embedded crack model: I. Basic formulation

The recently emerged idea of enriching standard finite element interpolations by strain or displacement discontinuities has triggered the development of powerful techniques that allow efficient modelling of regions with highly localized strains, e.g. of fracture zones in concrete, or shear bands in metals or soils. The present paper describes a triangular element with an embedded displacement discontinuity that represents a crack. The constitutive model is formulated within the framework of damage theory, with crack closure effects and friction on the crack faces taken into account. Numerical aspects of the implementation are discussed. In a companion paper, the embedded crack approach is combined with the more traditional smeared crack approach.