A high-fidelity constitutive model considering hydrostatic damage for predictions of high dynamic properties of concrete structures

This paper establishes a new high-fidelity constitutive model for predicting the high dynamic responses of concrete structures. The presented model incorporates the damage caused by hydrostatic pressure into the constitutive equations of concrete, while the hydrostatic damage induced strength and stiffness degradation behaviors have not been considered in existing models. In this model, two hydrostatic damage equations are introduced respectively to quantify the strength and stiffness degradation caused by hydrostatic damage. Based on this, a shrinking failure surface method is proposed for the failure criterion to capture the strength degradation, and a novel unloading/reloading law is developed for the equation of state to describe the stiffness reduction non-linearly. The model is implemented in the hydrocode LS-DYNA through the user-defined material subroutine. Numerical hydrostatic tests using a single element are conducted to verify the accuracy of the model firstly, and the corresponding predictions are in good agreement with the experimental results. Numerical simulations of penetration tests are then performed, where the damage mechanisms including hydrostatic damage and shear damage are identified. The comparisons between simulation and test results indicate that the presented model reflects the dynamic responses of concrete structures more accurately and reproduces the damage evolution of concrete more completely.