| This study presents the development of a hypoelastic three-dimensional model for the static analysis of reinforced and unreinforced concrete structures. The main concrete nonlinear behaviour characteristics are discussed along with a detailed analysis of the damage mechanisms of concrete up to rupture. Triaxial compression tests were carried out in this research to study, in particular, the effect of confinement on the damage progression and on the nature of the failure.;The main characteristics of the nonlinear behaviour of concrete, its triaxial behaviour, the steel-concrete interaction and the post-peak response, have been studied theoretically and numerically. New constitutive equations have been proposed: the cumulative damage of concrete along nonproportional loading paths is quantified with a scalar parameter; the volumetric expansion is considered through the use of non-symmetrical Poisson's coefficients; a simple equation for classifying the various modes of rupture is also proposed. Finally the post-peak behaviour of concrete is modelled using the principle of equivalent energy such that results are independent of the mesh size.;The proposed constitutive model has been validated under various stress conditions and histories and has always given satisfactory results, especially for non- proportional loading. Various types of reinforced concrete elements were modelled successfully: reinforced and unreinforced concrete members under uniaxial tension, reinforced concrete beams in shear, deep beams, reinforced concrete panels in biaxial state of stress, slabs exhibiting punching shear failure around columns, and laterally confined columns. |
