Simplified assessment of bending moment capacity for RC members with circular cross-section

Reinforced concrete (RC) members with circular cross-section are widely used in structural and geotechnical engineering (e.g. columns in frame structures, foundation piles, contiguous pile walls). Generally, for such members, the analysis is more complex than for rectangular cross-section and the problem is not sufficiently investigated in literature. Circular shape and uniform distribution of reinforcement along the perimeter cause some difficulties for a simple assessment of bending moment capacity. In this study, for RC members with circular cross-section, simplified methods for the evaluations of bending moment of resistance are presented. The performed analyses demonstrate that the design value of moment capacity, determined by the proposed approach, is very close to the results obtained applying rigorous methods. Furthermore, analysis results prove that in bending condition without axial load, the flexural strength depends, on the geometry of the section (i.e. radius and concrete cover) and on mechanical ratio of steel reinforcement by a very simple formula.