MODELING OF STRESS-STRAIN BEHAVIOR OF PLAIN CONCRETE USING A PLASTICITY FRAMEWORK

A constitutive model based on the theory of plasticity is proposed to characterize the stress-strain behaviour of plain concrete under three -dimensional loading. The model incorporates the third stress invarian t in the formulation that allows variation of shear strength with the orientation of stress paths on the octahedral plane. Also, it allows v ariation of the shape of the yield surface on the octahedral plane wit h confining pressure. An algorithm is developed and used to evaluate t he associated material constants in the optimum manner. Stress-strain responses are back-predicted for a number of stress paths using the pr oposed model and the results are compared with experimental observatio ns. Overall, good agreement between the experimental data and predicte d response is obtained.