The Axial Resistance of Nondisplacement Piles

Pile foundations have been used in construction for thousands of years but only in the last few decades has there been significant progress in the technology of pile installation. This progress on construction has not been matched by progress in the analysis and design of these foundation elements, which has lagged considerably. This is in large part due to considerable difficulties in analyzing both pile installation and the response of piles to various types of loadings rigorously. Given these difficulties, the profession has in general relied heavily on empiricism and relatively crude design approaches. This may well change due to pressures from different directions, particularly the progress in code design (the push towards load and resistance factor design in geotechnical engineering requires a much better grip on all the factors that need to be considered in calculating pile resistances and on the uncertainties in quantities and analyses, requiring sounder analytical frameworks) and economics (materials costs have been rising from multi-decade lows a few years back, a trend that would make it more economically interesting to have optimal designs). In this paper, we will examine the design process for axially-loaded non-displacement piles with a focus on assessing the strength of the recently developed analyses. We will show that, for these types of piles, design can be placed on a strong theoretical basis and discuss the implications for the future.