Effect of Shear on Collapse of Curved Beams

The principal structural actions in beams curved in plan are bending, torsion, and shear. Available methods of plastic analysis are based on the simplifying assumption that the effect of shear on the yield criterion is negligible. Clearly this is not a reasonable assumption in the case of reinforced concrete beams, and to account for the effect of shear, two three-dimensional bending-torsion-shear surfaces are proposed. The analysis of curved beams using the interaction surfaces is then described and the effect of shear on the modes of failure and the ultimate loads is demonstrated. As expected, the effect is significant and new modes of failure are found. Implications of the theory in the design of reinforced concrete beams are briefly described.