Experimental Study and Modeling of Reinforced Concrete Beams Strengthened by Post-Tensioned External Reinforcing Bars

The utilization of unbounded external reinforcing bars is one of the strengthening methods used after loading stage and before failure. The method has been used in different forms to strengthen members of reinforced concrete structures. To investigate the effect of utilization of post-tensioned reinforcing bars in this method of strengthening, a number of reinforced concrete beams was tested. Strengthening was carried out by attaching external bars on both outside faces of the beam in the level of internal flexural tension reinforcement. The behavior of strengthened beams was then studied both by experiment and modeling using ANSYS finite element structural software. In post-tensioning of external reinforcing bars, hydraulic jack was used. The results showed that this method of strengthening has increased the flexural capacity, and decreased the ductility of the beams. It was also shown that the increase in flexural strength caused by the utilization of unbounded external post-tensioned reinforcing bars was in reverse proportion with the percentage of internal flexural tension reinforcement. It was also concluded that the method is very effective for beams with lower percentages of internal flexural tension reinforcement.