I don't claim to be an expert in this area, but I know just enough to be
dangerous. The most important consideration in finite element modeling of
reinforced concrete is the non-linear behavior which occurs after cracking.
ACI Committee 446 has issued a State-of-the Art report, "Finite Element
Analysis of Fracture in Concrete Structures, ACI446.3R-97" which discusses
techniques for modeling the dicontinuities in the FEM mesh which result from
cracking. Regardless of what software you use, you might want to check out
this or other more recent resources, because the different techniques and
mesh patterns you use in the analysis can have significant effects on the
Matthew Carlton, P.E.