A New Generation of Composite Piles: Behaviour, Design Considerations and Field Applications

Piles used in bridges, structures and marine environments are typically produced using concrete, steel, and timber. High repair and replacement costs of these piles have led North American highway agencies and port authorities to investigate the feasibility of using durable materials such as fiber-reinforced polymers (FRP) in pile applications. This paper presents a new generation of composite piles composed of concrete-filled FRP circular tubes. The tube provides permanent formwork and noncorrosive reinforcement at the same time, leading to a simpler construction process. It also protects the concrete from severe environmental conditions and most importantly confines the concrete core, which increases its strength and ductility. The laminate structure of the FRP tubes can be engineered to provide the required strength and stiffness in the longitudinal and circumferential directions by controlling the proportions of fibers oriented in both directions. The structural performance of this type of piles under bending, axial loads and combined loading have been investigated experimentally, using large scale test specimens. Theoretical models and charts have been developed for analysis and design purposes. Field application of the composite pile in the first bridge ever built utilizing these piles, the Route 40 Bridge in Virginia, is introduced. Numerous field applications of this new pile as fender piles in marine environments in the United States are also introduced.