HUESPE Alfredo Edmundo
A macroscopic damage-plastic constitutive law for modeling quasi-brittle fracture and ductile behavior of concrete
P.J SÁNCHEZ; A E. HUESPE; J. OLIVER,; G. DIAZ,; V. SONZOGNI
INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS
JOHN WILEY & SONS LTD
Año: 2012 vol. 36 p. 546 - 573
Fracture and ductile concrete behavior, under general triaxial stress conditions, is presented. The model isparticularly addressed to simulate a wide range of confinement stress states, as also, to capture the stronginfluence of the mean stress value in the concrete failure mechanisms.The model is based on a two-surface damage-plastic formulation. The mechanical behavior in differentdomains of the stress space is separately described by means of a quasi-brittle or ductile material response:(i) For positive values of the mean stress (tensile states), an isotropic continuum damage modelwith strain softening is considered. In this context, and in order to avoid the Boundary Value Problemill-posedness induced by the softening law, a regularization technique based on the Continuum StrongDiscontinuity Approach (CSDA) is adopted, which results equivalent to a damage model with embeddedcohesive cracks providing anisotropic responses.(ii) A plastic model governs the material behavior when the mean stress is negative (confinement states).It is based on the classical plastic flow theory. In particular, a yield criterion similar to that of Willam andcoauthors, which depends on the three stress invariants, is used. Additional features defining the plasticresponse are: an isotropic strain hardening law and a non-associative flow rule.The paper presents the numerical implementation of the model using an efficient integration algorithm,namely, the Impl-Ex scheme. Several widely known experimental tests (such as uniaxial, biaxial andtriaxial tests) carried out on concrete specimens are used to calibrate and validate the performance of theproposed formulation. Finally, a classical 2D reinforced concrete beam example is analyzed in order toshow the predictive capability of the model in structural analysis applications.