FIELD AND LABORATORY TESTING OF UNFILLED AND CONCRETE-FILLED FRP COMPOSITE PILES

摘要

This paper investigates the use of load-bearing unfilled and concrete-filled Fiber Reinforced Polymer (FRP) composite piles in bridge applications. The research provides the basis for the structural and geotechnical design for FRP composite piles. Four 12.2 m long, 610 mm diameter FRP piles were driven in 2013 at a bridge site in Richmond, ME, as follows: a) One FRP shell (12.7 mm thick) filled with precast concrete, b) One FRP shell (25.4 mm thick) partially-filled with precast concrete, and c) Two unfilled FRP shells (25.4 mm thick). The piles sustained varying levels of damage at their top and bottom during the driving operation. All piles were extracted to document damage and tested under flexure and axial compression to assess residual strength and stiffness and differences from coupon level properties. Testing showed no degradation in pile flexural stiffness due to driving or cyclic loading but trends in strength loss were inconclusive. Driving does appear to affect the bond between concrete infill and the FRP shell through the creation of tensile cracks through the cross section of the concrete. The field and laboratory experimental data will be used to verify structural and geotechnical models and design and installation bases.