Reinforcement Calculation of Circular and Annular Cross Section

Circular and annular cross-section is one of the more common cross-section forms, such as water towers, piers, etc. But reinforcement calculation of these cross-sections is dual, the nonlinearity in width change and the nonlinear stress-strain relationship of concrete and reinforcement, which brings inconvenience to the calculation. In this paper, the corresponding calculation formulas are analytically derived and practical design charts (nomograms) are obtained. Based on stress-stain curve of concrete and reinforcement, five strain distribution regions were constructed. Via strains stress can be determined and then via the stress internal force can be computed, without application of the traditional equivalent rectangular stress block in concrete compression zone. The obtained dimensionless design charts can be applied to all load cases, such as uniform tension, tension with a small and large eccentricity, pure bending, compression with a large and small eccentricity and uniform compression. The calculation by using the design charts is simple and quick.