Drivability of Glass FRP Composite Piling

The low impedance of some glass fiber-reinforced polymer (GFRP) composite piles may limit their usefulness as bearing piles for structures due to drivability limitations. The high strength of glass fibers used in their manufacture makes the necessary pile cross-sectional area similar to that of a comparable steel pipe pile, while the compression wave velocity and mass density are much closer to that of concrete. This results in a very low impedance and limits the ability of the GFRP piles to be driven to high bearing capacities. A comparison of the drivability of four composite piles to conventional steel and concrete piles shows that all of the piles reviewed can be reasonably expected to attain design bearing capacities of 400 kN (90 kips), but that the extremely low impedance of glass fiber-reinforced matrix composite piles limits the ultimate capacity that can be achieved through impact driving.