External Posttensioning of Reinforced Concrete Beams Using a V-Shaped Steel Rod System

This study presents the development of an analysis method to predict the moments at first yielding and at ultimate strength of reinforced concrete beams strengthened using a V-shaped posttensioning steel rod system. The analysis requires determination of a total elongation of the external posttensioning rods, which is interdependent upon the neutral axis depth, deflection, and strains and stresses in beam components at both internal steel yielding and ultimate strength stages. The iteration algorithm was computationally programmed. The test results from a total of 14 full-scale beams were used to verify the analysis method that predicts the yield moment, moment capacity, and corresponding unbonded steel rod stresses. Finally, a flexural design method is developed for reinforced concrete beams externally posttensioned using a V-shaped steel rod system.