Stresses in Piles

Abstract

Factors controlling the static, long-term, and dynamic structural strength of pile sections are delineated and discussed for timber, concrete, and steel piles. It is shown that current design stresses for steel and concrete are reasonable, but that timber design stresses equal or exceed long-term constant load ultimate stresses. Reasonable limits to dynamic driving stresses are recommended. Other sources of load and stress in piles are discussed along with pile strength reducing factors; many of these factors are not now considered in design. It is concluded that the normal current pile-to-soil factor of safety of 2.0 is reasonable, and that pile structural factors of safety should always exceed the pile-to-soil factor of safety. It is also concluded that normal factors of safety should not be lowered until the profession attains a higher level of competence in inspection of pile installation.