ON NUMERICAL-INTEGRATION OF THE 5-PARAMETER MODEL FOR CONCRETE

Issues related to numerical integration of the William-Warnke version of the five-parameter model for concrete [K. J. William and E.P. Warnk e, Constitutive model for triaxial behaviour of concrete. IABSE Semina r on Concrete Structures Subjected to Triaxial Stresses (1974)] are di scussed. The constitutive equations are numerically integrated by an a lgorithm based on the operator split methodology. The cutting plane me thod and the full Newton-Raphson method are applied in the solution of the nonlinear set of equations in the plastic corrector stage and com parative analysis is performed. Attention is restricted to the perfect ly plastic behaviour of compressed concrete under plane stress conditi ons. Accuracy analysis is performed via iso-error maps for a represent ative range of loading conditions. Numerical examples are presented to test the effectiveness of the solution scheme.