SYMPOSIA PAPER Published: 01 January 1979

Capacity of Reinforced and Prestressed Concrete Pile Sections


Information needed to compute the nominal strengths of various pile cross sections that are subjected to combined compressive thrust and bending moments is presented, with examples of moment-thrust interaction diagrams for several typical kinds of pile sections.

The components of the factor of safety are examined, with particular emphasis on the reliable strength of the pile section. The use of a “strength reduction factor,” a multiplier that is less than 1.0, to establish a reliable or minimum expected failure load that is somewhat lower than the nominal failure load to be expected from an ideal member is discussed.

This strength reduction factor may vary with the number of piles in an individual footing and should be higher for piles that can be inspected than for those that cannot be inspected after completion. Precast piles and piles that are cast in permanent metal cylinders are examples of members that can be inspected to different extents, while piles cast-in-place in unlined holes or that have the liner pulled out of the hole after the concrete is cast are examples of members that cannot be easily inspected after construction.

Author Information

Gamble, WL
University of Illinois at Urbana-chapaign, Urbana, Ill.
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Developed by Committee: D18
Pages: 306–322
DOI: 10.1520/STP33736S
ISBN-EB: 978-0-8031-4740-9
ISBN-13: 978-0-8031-0291-0