Role of connected members on the load bearing capacity of compressed RC columns : Validation of ConSteel’s method

Reinforced concrete (RC) columns are crucial in construction, yet their design is challenging. Design typically involves first-order analysis, consideration of imperfections, and calculation of second-order effects, often done on an isolated column for simplicity, without precise consideration of adjacent elements. Although this approach is generally effective, it can lead to serious errors in certain cases. To investigate this problem, single columns under axial compression with different support conditions were first evaluated, followed by two columns connected by a stiff beam with hinged connections. The columns studied were either loaded at different intensities, had different boundary conditions, or had different cross-sectional areas. The evaluations included the nominal curvature method; the automatic nominal curvature method in ConSteel, which is a novel approximation of the second-order bending moments based on buckling shapes; and the general method. The results showed that if there is a significant difference in stiffness or in loading intensity between the connected members, the nominal curvature method can underestimate the bending moments compared to the general method. Therefore, in the case of irregular structures, more precise consideration of adjacent elements during design is essential to ensure safety. It was shown that this can be done automatically using the automatic nominal curvature method in ConSteel.