A nonlinear model for the elastoplastic analysis of 2D frames accounting for damage

Abstract

A simple and efficient procedure for non-linear analysis of frames is presen- ted, under the hypothesis that the non-linear effects, if appear, are concen- trated in the beam-ends.We consider a damage model based on Continuum Damage Mechanics, but affecting the cross-section as a whole. The elasto- plastic behaviour is included formulating the tangent elastoplastic stiffness matrix in such a way that the yield function, in terms of internal forces (axial, shear and bending moment), is affected by the damage in each plas- tic cross-section. After the verification of the model, an example of applica- tion is solved for different assumptions on the yield function (depending on the internal forces considered) with the damage being taken into account or disregarded. The differences on the collapse load, for each case, are shown and some conclusions obtained, among them that the method can evaluate in a more accurate way the load that causes the collapse of frames under increasing loading, considering a fully plastic non-linear analysis.