This work deals with a numerical investigation of the onset of inelastic instability in cruciform columns using the limit-point method. In this aim, a nonlinear buckling analysis was developed to determine the limit-point stress and the structure response during the post-buckling stage. Both total deformation and flow theories are used to describe the mechanical behavior. The numerical simulations were carried out considering cruciform columns with different material and geometric parameters. The obtained results were compared with experimental data from existing literature focused on the influence of the plasticity theory. The influences of the slenderness ratio and material parameters are discussed.