Damage propagation using novel G/XFEM strategies: computational aspects and numerical investigations

The nonlinear modelling of concrete structures demands strain-softening models that correctly represent the nucleation and propagation of damage. The typical concentration of such degrading phenomena in limited parts of the structure results in the strain localization that can be highly affected by the numerical algorithm used to solve the softening behaviour in concrete material. Finite Element discretization based on models from the continuum damage mechanics has not been able to overcome the numerical localization induced, anticipating the failure of the analysed problem. The Generalized/eXtended Finite Element Method is investigated here as an alternative to the standard Finite Element Method aiming to efficiently simulate the concrete strain-softening phenomenon. The enrichment strategy of the G/XFEM is used to obtain the nonlinear structural response using coarse meshes combined with different constitutive models from the continuum damage mechanics. Experimental results available in the literature are numerically reproduced and compared with equivalent approaches using FEM. Pathological behaviours that affect the quality of the results are evaluated. The possibility of using several combinations of different numerical methods and constitutive models is ensured by a framework for computational mechanics that encloses the G/XFEM implementation.