A Half Century of Tapered-Pile Usage at the John F. Kennedy International Airport

Tapered driven piles have been the deep foundation of choice ever since construction of and at the well-known John F. Kennedy International Airport (JFKIA) in New York City began in the late 1940s. Timber piles were used primarily for many decades but various brands of closed-end steel pipe piles have become preferred in recent years as engineers have sought ever-increasing allowable axial-compressive loads per pile. With currently available pile types it is now possible to routinely install tapered piles that have an allowable axial-compressive service-load capacity per pile in excess of 400 kips (1780 kN), with net ultimate axial-compressive geotechnical capacities of the order of 1000 kips (4450 kN). Fortunately, the use and load testing of piles at JFKIA has been relatively well documented. This extensive history and record of tapered-pile usage in one geologic setting provides an unusual opportunity to evaluate a new (in 2002) method for estimating the axial-compressive geotechnical capacity of tapered piles. The results of this evaluation are summarized in this paper and indicate very good agreement between measured and calculated capacities

Axial-Compressive Capacities of a New Type of Tapered Steel Pipe Pile at the John F. Kennedy International Airport

Tapered driven piles have been the deep foundation of choice at the well-known John F. Kennedy International Airport (JFKIA) in New York City ever since construction of and at the airport began in the late 1940s. For many decades naturally tapered timber piles were used primarily but various brands of closed-end steel pipe piles have become preferred in recent years as design engineers have sought ever-increasing allowable axial-compressive loads per pile. Toward the end of the 20th century, construction of new passenger terminals and a light-rail system called AirTrain at JFKIA pushed existing steel-piling alternatives to their performance limit in terms of both temporary driving stresses and permanent foundation loads. This led to the development of a new type of tapered steel pipe pile called the Tapertube. This paper discusses the rapid evolution of the Tapertube pile to the degree that it is now possible to routinely install piles that have allowable axial-compressive service loads per pile in excess of 400 kips (1780 kN), with net ultimate axial-compressive geotechnical capacities per pile of the order of 1000 kips (4450 kN). This paper also discusses the results from various types of load testing performed on Tapertube piles at JFKIA both during and after pile driving, and compares these results to capacities calculated using a new (in 2002) analytical method that has shown great promise for use with tapered driven piles. Finally, this paper also draws conclusions and makes suggestions as to how other tools such as dynamic measurements that are routinely used with tapered driven piles might be improved to better reflect the current understanding of how tapered driven piles develop most of their axial-compressive capacity

A New Type of Tapered Steel Pipe Pile for Transportation Applications

Piles with a variable perimeter over all or part of their length are generically called tapered piles. The benefit of using tapered piles when axial- compressive loads predominate, especially in 'friction' situations involving coarse- grain soils, has been recognized in principle for a long time. However, this benefit does not appear to have been fully exploited in practice, especially in transportation applications. Several recent events have produced a rebirth of interest in tapered piles, at least in U.S. practice. One was the development and commercial introduction of a new type of proprietary tapered steel pipe pile called the Tapertube. It was developed primarily to provide commercial competition to the long-established Monotube pile but it has also demonstrated that it is a structurally robust pile capable of withstanding the stresses of today's high-capacity design requirements. Of relevance to this conference is that Tapertube piles were essentially developed for, and eventually used extensively on, one of the larger transportation-related projects in the New York City metropolitan area in recent years, the major renovation and expansion work at the John F. Kennedy International Airport. This work included both terminal buildings and several kilometres of elevated light-rail structures as well as project-wide design for seismic loading. As a result, a comprehensive pile-load-test program was conducted to verify the performance of Tapertube piles under compressive, uplift and lateral loads