A plastic-damage uniaxial compression constitutive of concrete

Based on Irreversible Thermodynamic Theory and continuum damage mechanics, accounting the coupling relation of plastic stain and damage, an internal variable function was supposed between the plastic Helmholtz energy and the elastic Helmholtz energy. The expression of plastic Helmholtz energy was confirmed by proposing an expression of the internal function. Accounting the shape of Weibull distribution, the damage evolution equation of uniaxial compression concrete was deduced by establishing the relation of damage variable and damage energy dissipation rate, which was redefined by the new expression of plastic Helmholtz energy. And an empirical expression of plastic strain was given based on the plastic characteristic of the material. Uniaxial compression test results were used for verification of the model, which can reflect well the nonlinear feature and damage evolution of concrete.