Comparision of 3D stress-strain concrete models

The inelastic response of reinforced concrete buildings is strongly sensitive to the material stress-strain constitutive model adopted for concrete. This paper is a first step on an ongoing work to do a complete benchmark analysis of available concrete models. Consequently, this article quantifies the differences in the response of three well-known 3D stress-strain continuum concrete models: (i) the Hyperbolic Drucker-Prager (DPH) plastic model; (ii) the UNIlateral (UNI) damage model; and (iii) the Faría-Oliver-Cervera (FOC) plastic-damage model. Consistent algorithms in terms of the updated stresses and the tangent stiffness tensor for all these models were implemented in the ANSYS software using user-material FORTRAN routines adapted to solid-type finite elements. Models results were validated using a set of experimental benchmark tests subjected to uniaxial and biaxial stress states under monotonic and cyclic loading. Moreover, the unilateral (crack opening-and-closure) effect was compared among these models. A set of ten response parameters were compared relative to the experimental tests, e.g., the peak stress, the unloading stiffness at each loading cycle, and the total dissipated energy. Results show that the dissipated energy and the unloading stiffness in the last loading cycle, for all tests, leads to the largest errors.