This study presents a numerical investigation into the mechanical behavior of cold-formed steel upright columns used in storage rack systems, focusing on critical aspects such as buckling modes, nonlinearity, and perforation patterns. Based on previous experimental tests, finite element models were developed using shell elements in ABAQUS to simulate various column lengths and capture local, distortional, and global instability modes. The analysis explored material nonlinearity (ideal elasto-plastic behavior), geometric imperfections, and the impact of perforations on structural performance. Results showed good agreement with experimental data, particularly when initial geometric imperfections were included, emphasizing the importance of calibrating the imperfection scale factor. Perforations were found to significantly affect the critical load but not the instability mode. This research enhances understanding of rack column stability and supports further parametric studies aimed at developing accurate design curves for cold-formed steel rack systems.