Simplified evaluation of the ultimate strength of RC circular members subjected to axial force, bending moment and shear force

The paper proposes a simple analytical tool for the evaluation of the shear strength of reinforced concrete circular, solid or hollow, slender columns endowed with shear reinforcement and subjected to axial force, bending moment and shear force. The proposed method considers the sole beam action by means of simplified stress fields and simultaneously satisfies the equilibrium under the above combined internal forces. The paper identifies basic points in the N-M-V ultimate interaction curve and describes the procedures for the evaluation of the internal forces of these points as well as the procedures for the evaluation of the internal forces of the points in between. The method is first applied to a set of circular solid columns with different geometric and mechanical properties and a comparison is drawn between the shear resistance resulting from the simplified method and that from a more complex non-linear mathematical programming problem proposed in the past by one of the authors. Then, to demonstrate the value of the method and define the field of its accurate application, the proposed method is applied to circular (solid or hollow) columns tested in laboratory by other researchers. Finally, the results of the proposed method are compared with those of some code formulations.