Moment–Curvature and Failure Analysis of Reinforced Concrete Circular Columns

This study presents a numerical investigation of the moment–curvature behavior and failure characteristics of reinforced concrete (RC) circular columns using a MATLAB-based fiber section model. The analysis incorporates the Mander Model for concrete and an elasto-plastic model for reinforcing steel to capture realistic material response. Results show a stable and ductile moment–curvature relationship with a smooth transition from elastic behavior to a plastic plateau, indicating high energy dissipation capacity. The neutral axis gradually shifts toward the compression zone with increasing curvature, reflecting nonlinear stress redistribution. A high ductility ratio (μ) is observed, highlighting the suitability of circular RC columns for seismic applications. Additionally, stiffness degradation confirms the reduction in flexural rigidity (EI) after cracking and yielding. The study demonstrates that fiber-based numerical modeling is an efficient and reliable tool for predicting the strength, ductility, and failure behavior of RC circular columns.