Thermodynamical assessments to model steel concrete interface behaviour including corrosion effects

To model the three dimensional response of reinforced concrete structures subject to complex loadings, the local constitutive model for concrete have to account for different nonlinear mechanisms such as :Stiffness decrease due to cracks and stiffness recovery due to closing cracks under cyclic loadings, inelastic strains due to the material heterogeneity, frictional sliding due to the cracked surfaces rugosity. In this contribution, a three dimensional behaviour constitutive set of equations for modelling the mechanical response of quasi brittle materials such as concrete is presented. The formulation is based on the thermodynamic framework of irreversible processes in order to guaranty its physical consistency and to allow the opportunity to perform large scale computation at the structural case. Among the different choices allowed to model microcraking (anisotropic damage for example), a single scalar damage variable has been introduced in order to take into account of non linearities due to micro cracks effects, including the non symmetric response for tensile loading and compressive state of stresses. Based on strain decomposition in deviatoric and hydrostatic parts, the stiffness recovery is associated to the hydrostatic behaviour while frictional sliding is only concerned by the deviatoric one. The influence of sliding which occurs between the cracked surfaces has been considered in order to represent accurately hysteretic loops as well as the energy dissipation at the material scale. Related numerical aspects are presented ensuring convergence and robustness for structural casestudies. The integral form of non local models has been retained to avoid any spurious mesh dependency due to strain softening