Performance of a Laterally Loaded Composite Pile at the Nottoway River Bridge

Because steel and concrete piles can degrade in marine environments, composite piles employing fiber reinforced polymer to replace and/or protect steel and concrete are being considered for support of highway bridges. Although such alternative piles have relatively high initial costs, they may have reduced life-cycle costs resulting from reduced maintenance costs and longer service life. However, there are impediments to using composite piles, including a paucity of documented case histories and a lack of verified analysis and design procedures. This paper describes use of composite piles at the Route 40 bridge across the Nottoway River in Virginia. One bent of the bridge is entirely supported on composite piles formed of fiber reinforced polymer tubes filled with concrete and without any steel reinforcing. A test pile program was performed at the bridge site, in which a prestressed concrete pile and a composite pile were loaded laterally using a Statnamic device. Both test piles exhibited about the same lateral load versus deflection response up to a load of about 50 kN. Beyond this, the composite pile response was much less stiff than the prestressed concrete pile response. Calculations of lateral load versus deflection were made for both test piles using the p-y methodology. The same set of p-y parameter values provided reasonably good agreement between the calculated response and the results of the Statnamic tests. This indicates that standard methods of calculating the load-deflection response of concrete piles can be used for composite piles, at least for the type of composite pile employed at the Route 40 bridge.