Piles are a fundamental part of most offshore structures, thus assessment of pile capacity is critical for the design and installation of offshore structures. Currently, there are various codes that provide guidance on the pile capacity assessment. The most common ones are from the American Petroleum Institute (API) and Det Norske Veritas (DNV). As each code provides a slightly different design approach and utilises different safety factors, it is often not easy to compare the pile designs of different code directly. Furthermore, the most appropriate design methodology is often chosen based on the available input parameters, such as geotechnical properties or cone penetration test (CPT) results. For a single design case, adapting the different codes can result in different pile length requirements, which are purely due to different methodology and associated safety factors used in codes. This paper aims to provide an overview of all common pile design methodologies and present a comparison of design pile lengths resulting from the use of these codes.
The assessment of the axial bearing capacity of piles varies in different codes in terms of methodology and safety factors. As a result, the outcome of the pile length assessment differs from one code to another. Nevertheless, axial bearing capacity of the pile is a single value and perhaps has an offset from the results obtained from bearing capacity assessment based on various methods outlined in different codes. The objective of this paper is to present the variation of pile length for a single compressive load based on methodologies presented in the codes from the American Petroleum Institute (API, 1993, 2000) and (DNV, 1992, 2008, 2011).
API and DNV codes describe slightly different approaches to assess the axial bearing capacity of a pile.