Experimental investigation of full-scale post-tensioned composite AASHTO beams prestressed with carbon-fiber-reinforced polymer cables

This paper reports on an investigation of the flexural behavior of post-tensioned composite AASHTO beams under flexural monotonic and fatigue loading. Five 39.5-ft-long (12-m) post-tensioned beams with 0.76-in.-diameter (19-mm) prestressing carbon-fiber-reinforced polymer (CFRP) cables were studied. Three beams were post-tensioned with unbonded cables, and the other two beams were post-tensioned with bonded cables. The fatigue resistance and the effect of tendon profile (straight versus draped) were investigated. The results showed that the two beams with unbonded tendons survived 2.3 million fatigue cycles with an insignificant effect on the deformation and stiffness of the beams. At the ultimate load, the beams with unbonded cables showed greater deformation compared with the counterparts with bonded cables; however, the flexural capacity of the unbonded beams was lower. Different analytical models for estimating the flexural capacity of the beams were assessed against the experimental results to determine the applicability of these models to full-scale CFRP post-tensioned beams.