Ultimate Partially Stress for Unbonded Post-Tensioning Tendons InPrestressed Beams

In this project, an attempt has been made to investigate the behavior of fully or partially prestressed beams with unbonded post-tensioning strands. The following variables were considered : percentage of reinforcement, shape of members, strength of concrete, span-depth ratio, and initial stress in the strands. Four groups of beams (33 total beams) were tested. This paper deals with stress in the strands at the ultimate stage of the beams. A suitable method for the prediction of the ultimate stress f ps in the prestressing reinforcement is also proposed. These values are compared with measured stresses and stresses obtained from ACI equations. Measured f ps values are reported in this paper.