Model of damage for steel frame members

The main purpose of this paper is to propose a model of damage for steel frame members based on the methods of continuum damage mechanics and the concept of the plastic hinge. It first describes a particular model of continuum damage for metals, the Lemaitre's model. It is then shown, on the basis of experimental results, that this model could be used in the analysis of steel frames if it is combined with a multilayered procedure. In the last part of the paper, a new model for a frame member with damaged-plastic hinges is proposed. In this model, a set of internal variables that measure the state of damage of the hinges is introduced. These variables and the conventional plastic deformations define the behavior of the hinges. It is shown that the uniaxial behavior of the material and the behavior of the hinges under flexural effects have the same general form. A yield function for a damaged-plastic hinge with kinematic hardening and a damage evolution law are then proposed.