DAMAGE IN CONCRETE - THE UNILATERAL PHENOMENON

Because the damage in a solid results from microscopic movements, we d ecided to include the power of these microscopic movements in the powe r of the internal forces. The microscopic velocities are related to th e damage rate. The power of the internal forces that we choose depends on the damage velocity and its gradient to take into account the inte ractions. Models from this theory are presented. They are coherent fro m the mechanical and mathematical points of view. The numerical comput ations show no mesh sensitivity. They describe with good agreement the main experimental properties. Concrete is chosen as an example to ill ustrate the theory. A model using two damage quantities is also presen ted. It gives a description of the unilateral phenomenon observed in c oncrete.