Factors affecting the external prestressing stress in externally strengthened prestressed concrete beams

The experimental and the analytical results showed that the studied factors have the same effect on both steel (up to yield) and Parafil ropes though this effect is greater in case of steel tendons. Also, factors such as tendon profile (straight or deviated), high strength of the concrete, effective tendon depth, number of deviators should be taken into consideration when calculating the ultimate stress in the external tendons.