Limit analysis of reinforced concrete beams subjected to pure torsion

A limit analysis method for predicting the torsional strength of reinforced concrete beams is introduced in this paper. This method uses the modified Coulomb-Mohr failure criterion as the constitutive law of concrete, and assumes the plastic dow of concrete after yielding to be associated with its failure surface. A generalized formulation for energy dissipation rate along a yield line in accordance with the failure criterion as well as the upper-bound method are employed in this research. The ultimate strength of reinforced concrete beams subjected to pure torsion is then predicted by the work equation based upon the energy dissipation rate and the permissible failure mechanism at the ultimate state. The theoretical torsional strengths are compared with the existing experimental results and they appear to be in good agreement.