Conventional steel and concrete piles are widely applied in civil engineering industries with long time experience and many advantages. However, steel pipe piles, a sort of most common steel pile, are prone to losing their structural integrity over time due to corrosive and humid conditions. Moreover, concrete piles such as in-situ concrete piles and pretensioned spun high strength concrete (PHC) piles are subject to deterioration of their long-term structural durability. Therefore, Hybrid FRP-concrete composite pile (HCFFT) was developed. HCFFT is consisted of pultruded FRP (PFRP) unit module, filament winding FRP which is in the outside of mandrel composed of circular shaped assembly of PFRP unit modules, and concrete which is casted inside of the circular tube shaped hybrid FRP pile. Therefore, PFRP can increase the flexural load carrying capacity, while filament winding FRP and concrete filled inside can increase axial load carrying capacity. In this paper, field loading experiments were conducted to evaluate field bearing capacity of HCFFT pile with connection and HCFFT pile without connection.

HCFFT (Hybrid Concrete Filled FRP Tube) is consisted of pultruded FRP unit module, filament winding FRP which is in the outside of mandrel composed of circular shaped assembly of pultruded FRP unit modules, and concrete which is casted inside of the circular tube shaped hybrid FRP pile. The pultruded FRP can increase the flexural load carrying capacity and the filament winding FRP can provide the confinement for the concrete filled inside. The axial and flexural load carrying capacities of small diameter HCFFT piles were evaluated through the experimental and theoretical studies. In this study, we suggest the cross-section and manufacturing process of large diameter HCFFT pile which is expected to improve the quality and productibility of large diameter HCFFP pile.