Construction, Strength, and Driving Performance of Carbon-Fiber-Reinforced Polymer Prestressed Concrete Piles

Carbon-fiber-reinforced polymers are advantageous because of their resistance to corrosion, particularly in aggressive or saltwater environments. This study examined carbon-fiber-composite cable (CFCC) in prestressed concrete piles for bridge foundations. Five 24 in. (610 mm) square piles were constructed and prestressed with 0.6 in. (15 mm) diameter CFCC. Strain measurements during detensioning indicated that the transfer length was less than design code predictions for steel prestressing strands. Additional tests showed that the development length was also less than code predictions. A bending test on a 40.0 ft (12.2 m) long pile resulted in a flexural strength that was 8% greater than the theoretical flexural strength, and the pile had good ductility with a midspan deflection of more than 9.0 in. (230 mm) at failure. Two 100 ft (30 m) long piles, monitored under hard-driving conditions at a bridge construction site, behaved well with no major damage or loss of prestress.