Evaluation of Brazilian standard ABNT NBR 6118 procedures for calculating the second‐order effects of reinforced concrete slender columns subjected to uniaxial bending

This paper evaluated the Brazilian Standard ABNT NBR 6118:2014 procedures for calculating the second‐order effects of reinforced concrete columns subjected to uniaxial bending. The theoretical results were compared to 187 experimental results of normal and high strength reinforced concrete slender columns under short‐term loading. The most influencing parameters were analyzed: cross‐section thickness, slenderness ratio, longitudinal steel ratios and initial eccentricity of the axial load. The mean value of M test/M calc ratio resulted closest to the unity for the model column method with approximate curvature. In general, this method leads to less scatter in comparison to the other methods. Some errors in reinforced concrete slender columns testing were discussed: constructive errors, misalignment of the column, variations of support conditions and errors in instruments readings. All of those errors have significant impact in the variability of the results of the comparative study.