Abstract

A constitutive model devised for the analysis of concrete structures, and suitable for generic two- or three-dimensional applications, is presented and validated. For plain concrete a tension-compression distinguishing stress split is performed, and two scalar damage variables account for the degradation induced by the tensile and compressive stress components. As outcomes the model reproduces the stiffness recovery upon load reversal, and it captures the strength enhancement under multiaxial compression. Besides, the simple formulation as well as the extremely reduced number of parameters involved in the concrete model makes it quite suitable for the analysis of real structures, and constitutes a useful design tool. As regards to the nonlinear performance of the steel reinforcement, the explicit Giuffrè–Menegotto–Pinto model is adopted. Efficiency of the global model is illustrated via two seismic applications: one concerning an arch dam, and the other a six-floor reinforced concrete wall. The latter application is presented for validation purposes.

Abstract

Within the framework of Continuum Damage Mechanics some isotropic scalar damage models for concrete are revisited, with emphasis on a recent one proposed by the authors. This scalar damage model is based on the assumption that a stress split is required to capture unilateral behaviour exhibited by concrete when passing from tension to compression. Similar assumptions are pursued on many scalar damage models, yet with many differences being encountered on the strategies adopted for the implementation of such split, which sometimes is performed over the strain tensor. In this paper a discussion on the implications of those splits is conducted, as well as on the norms that define the elastic domain in the stress space. For the proposed damage model a strain-driven formalism is adopted, but the stress split is performed on the effective elastic stress tensor, which is shown to correspond to a split of the Cauchy stress tensor. This strategy improves the algorithmic efficiency as much as required for the seismic analysis of large-scale problems, and circumvents many of the drawbacks present in similar damage models. Besides, two scalar damage variable are introduced as internal variables, as well as an inelastic strain tensor. Efficiency of the proposed constitutive model is illustrated through numerical applications. Algorithmic implementation is also detailed.