Influence of cross-section shape on the stress-strain state of centrally compressed reinforced concrete columns

The study focuses on centrally compressed reinforced concrete columns with various cross-sectional shapes, including square, rectangular, cruciform, T-shaped, and L-shaped sections. In structural engineering, the load-bearing capacity of columns is typically enhanced through transverse reinforcement, external jackets, or composite confinements that create a triaxial compression effect. However, the influence of cross-sectional geometry on the formation of a 3D stress state has not been sufficiently investigated. A numerical analysis of centrally compressed reinforced concrete columns with different cross-sectional configurations was carried out using the finite element method in the LIRA-SAPR software package, accounting for the nonlinear behavior of concrete. The results indicate that the shape of the cross section has only a minor effect on strength characteristics (differences below 3%), but significantly affects the distribution of volumetric stress zones, which are pronounced in T- and L-shaped columns when dilation effects are considered. It was found that volumetric confinement primarily develops in the support regions and has little influence on the overall structural performance of the columns. Future research will focus on eccentrically loaded columns and on the effect of external confinement systems, including concrete-filled steel tubes, steel jackets, and indirect reinforcement, on the formation and evolution of the 3D stress-strain state of reinforced concrete elements. The proposed research direction confirms the practical relevance of the study and the potential for further investigation in this field.