Axial and Lateral Load Performance of Two Composite Piles and One Prestressed Concrete Pile

Composite piles use fiber-reinforced polymers (FRPs), plastics, and other materials to replace or protect steel or concrete, with the intent being to produce piles that have lower maintenance costs and longer service lives than those of conventional piles, especially in marine applications and other corrosive environments. Well-documented field loading tests of composite piles are scarce, and this lack of a reliable database may be one reason that composite piles are not in widespread use for load-bearing applications. The purpose of this research is to compare the axial and lateral load behavior of two different types of composite test piles and a conventional prestressed concrete test pile at a bridge construction site in Hampton, Virginia. One of the composite piles is an FRP shell filled with concrete and reinforced with steel bars. The other composite pile consists of a polyethylene plastic matrix surrounding a steel reinforcing cage. The axial structural stiffnesses of the prestressed concrete pile and the FRP pile are similar, and they are both much stiffer than the plastic pile. The flexurel stiffness of the prestressed concrete pile is greater than that of the FRP pile, which is greater than the flexural stiffness of the plastic pile. The axial geotechnical capacities of the test piles decreased in order from the prestressed concrete pile to the FRP pile to the plastic pile. The prestressed concrete pile and the FRP pile exhibited a similar response for lateral load versus deflection, and the plastic pile was much less stiff in lateral loading.