A comparative study of state-of-the-art constitutive models for concrete failure under shear-dominated stress states

While state-of-the-art constitutive models are able to reproduce the mechanical behavior of concrete under compressive and tensile loading with satisfactory accuracy, more complex failure modes caused by shear or mixed-mode loading often result in inaccurate predictions in numerical simulations. Although numerous constitutive models have been developed in recent decades, the systematic validation and objective performance assessment of such models have received comparatively little attention. The present contribution assesses the predictive capabilities of state-of-the-art constitutive models under shear-dominated and mixed-mode failure. A gradient-enhanced extension of the Microplane M7 model, originally proposed by Caner and Bažant (2013) , is compared to two established approaches: a gradient-enhanced extension of the Concrete Damage-Plasticity model by Grassl & Jirásek (2006) and the gradient-enhanced Microplane Damage-Plasticity model by Zreid & Kaliske (2018) . The predictive accuracy of these models is assessed using three-dimensional implicit finite element simulations of benchmark tests involving notched prismatic specimens subjected to torsional, antisymmetric four-point, and combined shear-tensile loading. Special focus is placed on the models’ ability to predict the load-bearing capacity and post-peak behavior, including crack initiation and propagation. The results show that two of the three investigated models provide accurate predictions of shear-dominated concrete failure, while the third exhibits limitations under such loading conditions, indicating that further refinement remains necessary.