Analysis and field tests on the performance of composite tubes under pile driving impact

Composite tubes provide a feasible alternative to concrete piles by eliminating formwork, reinforcing cage, and additional corrosion-deterrent cover. Field driving of concrete-filled composite tubes showed no damage to the tube or concrete. Driving stresses in filled tubes were found comparable to those for prestressed concrete piles. Empty tubes may buckle or rupture under driving impact, unless driven at shallow depths and in soft soils, or with a steel mandrel. A detailed parametric study using the wave equation further confirmed that there is no difference in the drivability of filled FRP tubes and prestressed concrete piles of the same cross-sectional area and concrete strength. The typical refusal rate for conventional concrete piles can be safely adopted for filled tubes. However, empty tubes are susceptible to compression failure, and can only endure diving stresses up to 40–50% of the refusal rate of concrete piles.