Effects of driving forces and bending fatigue on structural performance of a novel concrete-filled fibre-reinforced-polymer tube flexural pile

The effects of driving forces and high-cycle fatigue on the flexural performance of a novel pile consisting of a concrete-filled glass-fibre-reinforced polymer (GFRP) tube (CFFT) are investigated. A 367 mm diameter CFFT pile was driven and then extracted from the ground. Two 6 m segments cut from the upper and lower ends of the pile were tested to failure under monotonic bending and compared with a similar undriven CFFT pile. In addition, a 625 mm diameter CFFT and a conventional 508 mm square prestressed concrete pile of similar moment capacities, both 13.1 m long, were driven, tested in the field under lateral loads, and compared. It was found that driving forces have a marginal effect (about 5% reduction) on the flexural strength of CFFT piles. Also, CFFT piles have larger deflections than prestressed piles do. Because the GFRP tube is the sole reinforcement for the CFFT system, a comprehensive fatigue test program was conducted: coupons cut from the tube were tested under cyclic loading at various str...