I plan to explore the Saint-Venant torsion problem applied to prismatic bars with elastic-plastic behavior. Wagner and Gruttmann have developed a finite element method to obtain the elastic/plastic stresses of a bar using a single load step. In particular, I will present the constitutive model that they have developed, and then use ABAQUS to apply Wagner and Gruttmann’s model to various cross-sections. I will try to reproduce their results for some simple cross-sections, as well as exploring some more complicated cross sections. I will compare my numerical results with analytical results for the various cross-sections.