Numerical Analysis and Design of Short Reinforced Concrete Columns Subjected to Axial Load and Biaxial Bending Using Abaqus

Abstract

Short reinforced concrete (RC) columns in multistory structures are frequently subjected to combined axial load and biaxial bending arising from wind, seismic actions, and construction eccentricities. Accurate prediction of their nonlinear response remains challenging due to complex stress interactions and limitations inherent in simplified code-based interaction formulations. This study investigates the structural behaviour and failure mechanisms of a short RC column using three-dimensional nonlinear finite element modelling in ABAQUS, complemented by analytical design checks in accordance with BS 8110. Concrete (C25) was modelled using the Concrete Damage Plasticity (CDP) framework, while reinforcement was represented as elastic–plastic steel. Appropriate discretisation (C3D8R and T3D2 elements), embedded interaction, and geometric nonlinearity were implemented to ensure numerical stability and mesh convergence. The simulations revealed pronounced nonlinear behaviour, with peak compressive stresses exceeding 40 MPa and yielding initiated at a strain of approximately 0.002. Post-peak softening was marked by significant stiffness degradation and ultimate lateral deflections exceeding 50 mm, indicating limited ductility under biaxial effects. Damage indices showed concentrated mid-face crushing (DC > 0.8) and severe corner cracking and spalling (DT > 0.9). Comparison with BS 8110 predictions indicated a 20–30% overestimation of load capacity at higher eccentricities, underscoring the influence of biaxial interaction and progressive damage not fully captured by simplified design equations. Although limited to static loading and ideal bond assumptions, the findings demonstrate the robustness of CDP-based modelling and highlight its relevance for performance-based assessment and safer column design under multiaxial loading.