Ultimate strength of reinforced concrete circular members subjected to axial force, bending moment and shear force

Over the last few decades a significant effort has been made to achieve accurate evaluation of the resistance of reinforced concrete elements subjected to pure shear or combined internal forces including shear. As regards the latter, continuum models characterized by simplified stress fields have recently been applied by one of the Authors for the evaluation of the ultimate capacity interaction diagram of rectangular reinforced concrete cross-sections undergoing combined axial force, bending moment and shear force. This paper illustrates the natural progress of these studies and describes an analytical tool for the calculation of the ultimate strength of reinforced concrete columns with circular cross-section. The proposed method is based on the application of the static theorem of limit analysis and takes into account both truss and arch effects. To ascertain the accuracy and reliability of the method, the relations developed are applied with reference to a large number of tests reported in the literature and a comparison between the theoretical and experimental results is drawn. Finally, the predictions of the proposed method are compared with those of other simplified methods present in the literature.