"Field Installation, Splicing, and Flexural Testing of Hybrid FRP/Concrete Piles"

Synopsis: Concrete-filled fiber-reinforced polymer (FRP) tubes (CFFTs) are becoming increasingly popular in pile applications. An experimental program was undertaken to address the drivability and effect of driving forces on CFFT piles as well as the use of splices. In this program, four full-scale piles, 357 mm in diameter, and 13.7 m long, including a spliced pile, were driven into the ground and then extracted. The piles were cut into 6 m portions that were used for beam tests on spliced and unspliced specimens and 0.3 m portions used for material characterization of the FRP tube and push-off tests to evaluate the bond strength between the concrete core and FRP tube. Test results were compared to those of control specimens, which were not subjected to driving forces. In total, six beam tests, 28 push-off tests and 54 tension coupon tests were conducted. Test results indicate that driving forces have marginal effect, about 5% reduction, on the flexural strength of both unspliced and spliced CFFT piles, on bond strength and on the tensile strength of the FRP tube. It is also shown that the mechanical splice used in this study performed well and was capable of developing a moment resistance, 7% higher than that of the CFFT pile.