Nonlocal formulation of the modified K&C model to resolve mesh-size dependency of concrete structures subjected to intense dynamic loadings

With the aid of commercial concrete material models, numerical simulation plays an increasingly important role in the analyses of dynamic responses of concrete structures subjected to intense dynamic loadings. Mesh-size dependency is a known problem of local material models used to simulate concrete due to strain softening, which is observed in numerous simulations. In this paper, the widely used regularization technique for quasi-static problems, smeared crack approach, is evaluated and proven to be ineffective for dynamic situations. To resolve the mesh-size dependency of concrete under dynamic loadings, the nonlocal formulation of the modified K&C (MKC) model proposed in our recent work is presented. The nonlocal MKC model is validated against four experiments, covering a wide range of stress/loading conditions, namely: Modified Split-Hopkinson Bar (spalling) test, Split-Hopkinson Tension test, Split-Hopkinson Pressure Bar test, and reinforce concrete beam subjected to blast loading. The numerical predictions are mesh objective and in good agreement with the corresponding experimental data.