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.
