| Conventional pile materials (steel, concrete, and wood) can encounter serious corrosion problems in industrial or marine environments. Fiber Reinforced Polymer (FRP) composites are potentially suitable for these harsh environments. Since FRP composites have anisotropic properties, the theories developed for steel piles cannot be readily adopted to evaluate the performance of FRP piles. Interface shear tests in this study showed that the interface behavior between FRP composites and granular materials depended on the relative surface roughness, the normal stress level, the initial density of the soil mass and the angularity of particles. A relationship between interface friction coefficient and these factors was identified. Based on the Mindlin contact theory and the state variable friction law, a strain-softening constitutive law for interfaces was proposed. A new nonlinear solution for axial deformation of a single vertically loaded pile, which considers the partial slip development along the pile shaft during loading, was developed during this study. To account for the anisotropic properties of FRP composites, the Timoshenko beam theory was adapted to derive the solutions for buckling loads and load-deflection responses of vertically and laterally loaded FRP piles. |
