This paper describes a nonlinear numerical model capable of predicting the response up to failure of unbonded, partially prestressed, continuous, concrete beams, and presents a comparison of results from the model against test data. Loading pattern, type of loading and degree of concrete confinement are shown by means of a parametric study to have a significant effect on the tendon stress at ultimate. Finally, modifications are suggested to the current A23.3-94 Canadian Code equation for predicting the tendon stress at ultimate in concrete members prestressed with unbonded tendons, in order to consider the contribution from all plastic hinges likely to develop under a particular pattern of loading. Predictions from the modified equation are shown to be in good agreement with available test data.
