Flexural Behavior of Concrete Beams Internally Prestressed with Unbonded Carbon-Fiber-Reinforced Polymer Tendons

The objective of this research was to experimentally investigate the effects of the prestressing reinforcement ratio, the magnitude of the prestressing force, the loading type, and the sectional shape on the flexural behavior of beams internally prestressed with unbonded carbon-fiber-reinforced polymer (CFRP) tendons. Four rectangular and three T-beams were tested. Test results have shown that, even for the unbonded prestressing ratio less than the balanced ratio of the bonded equivalent, unbonding the CFRP tendons could relieve tendon strains along the beam span and delay the rupture of CFRP tendons. Improved ductility was observed for the rectangular beams prestressed with unbonded CFRP tendons and non-prestressed auxiliary bonded steel bars when compared with prestressed beams that have bonded CFRP tendons. DOI: 10.1061/(ASCE)CC.1943-5614.0000306. (C) 2013 American Society of Civil Engineers.