This paper describes an approach, based on the concepts of continuum d
amage mechanics and standard inelastic analysis of reinforced concrete
(RC) frames, to the modeling of the hysteretic behavior of RC frames.
A frame member is considered as the assemblage of an elastic beam-col
umn and two inelastic hinges, as in the conventional lumped plasticity
models. Three sets of internal variables, which measure plastic rotat
ions and the state of damage of the member, are introduced. An express
ion for the flexibility matrices and the complementary strain energy o
f a member are proposed as a function of these internal variables. The
resulting model can be classified as ''unilateral,'' i.e., it is assu
med that damage due to positive actions has no influence in the behavi
or under negative action due to the closure of cracks when moments cha
nge sign. The accuracy of the model is verified by simulating various
experiments for which data were available in the literature. The model
is very simple in nature and as a result is not comprehensive; howeve
r, the approach presented is amenable of further generalizations.