Gradient plasticity in numerical simulation of concrete cracking

摘要

In a continuum approach to concrete fracture a gradient-dependent plasticity theory is used to preserve the well-posedness of the problem in the softening regime and to obtain finitely sized fracture process zones. The theory employs a Rankine failure surface which is dependent on an equivalent fracture strain measure as well as on its Laplacian. The finite element algorithm employs a discretization of the equivalent fracture strain in order to solve the differential consistency equation in addition to the usual discretization of the displacements. A series of concrete fracture simulations are performed: a beam in four-point bending, a specimen in direct tension, a Single Edge Notched (SEN) beam and a Double Edge Notched (DEN) specimen. A proper regularization effect in the sense of a finitely sized fracture process zone and a reasonable agreement with experimental predictions are found.