Dear Xuejian,

I am sorry, but I don't completely understand, what "cantilever reinforced concrete shear wall with I-section" means. If you could attach a simple figure, or describe the structure better, it will help me. I do understand the "cantilever reinforced wall" but I am confused with "I-section". Anyway, the layered cross section could not be combined with plane stress elements at the moment, it can be combined with beam, plate, and shell elements only. But in general, when solving a reinforced concrete wall, I would suggest to use plane stress elements to model the concrete only and add the reinforcement explicitly using bar elements. oofem has many features (hanging nodes, etc.) that allow to place such reinforcement arbitrarily into "independent concrete mesh" and to account for bond-slip behavior, reinforcement yielding, etc.

Concerning the model for concrete:
The choice of models for concrete capturing the nonlinear behavior in compression and tension is limited.
I would suggest to use either Mazars model (still isotropic damage, but tensile and compressive damage are taken into account) or much more general microplane model.
For the steel, you can use "j2mat" material model, implementing j2 plasticity with hardening. (Now I figured out that it is not documented!).
The corresponding record is:

j2mat #  E # n # Ry #  tAlpha # d # ihm #

where E - Young modulus,
n - Poisson ratio,
Ry - yield stress,
tAlpha - dilatation coeff.
d - density
ihm - hardening moduli - hardening is linear aftre reaching yield stress.

Borek