An Appraisal of API RP2A Recommendations for Determining Skin Friction of Piles in Sand

Toolan, Fe; Lings, ML; Mirza, U. A.A.

doi:10.4043/6422-ms

Cited by 24 publications

(13 citation statements)

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“…Mansur & Kaufman (1956) Old River (Low-Sill) Mey et al (1985) l-c 0.914 Toolan et al (1990) an effect occurs in the friction profile near the pile tip that is opposite for the two loading types, generating increased friction for tensile loading and decreased friction for compressive loading.…”

Section: 5mentioning

confidence: 99%

“…Thus, effects of friction degradation are accounted for, at least in a simplistic way. The approach proposed by Toolan et al (1990) essentially provides an upper and lower bound to the ratio B = t&r"', with a sharp jump from the upper value (in the lower 10m of the pile) to the lower value over the remainder of the pile shaft. The sudden reduction in fi is clearly an idealization, and the fixed lower limit of /?…”

Section: Shaft Frictionmentioning

confidence: 99%

“…Following Toolan et al (1990), it is helpful to postulate a minimum value of b, which will be a function of the minimum ratio of ur'/gv' (perhaps linked to the active earth pressure coefticient K,) and tan 6. This minimum value will be reached only with very long piles.…”

Section: Shaftfriction Distribution Along the Pile Shaftmentioning

confidence: 99%

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Design of driven piles in sand

Randolph

Dolwin²,

Beck³

1994

Géotechnique

257

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Estimation of the axial capacity of piles driven into sand involves considerable uncertainty, and design rules are generally not consistent with the physical processes involved. This Paper reviews current understanding of the factors that determine the axial capacity of piles driven into sand, and outlines a new framework for design which takes account of the physical processes, is consistent with the existing database of load test results, and is sufficiently flexible to permit refinement as new data become available. It allows for the effects of confining stress on the frictional and compressibility characteristics of sand, and hence on endbearing capacity. In keeping with field observations, shaft friction is assumed to degrade with driving of the pile past a particular location, from an initial maximum value linked to the local end-bearing capacity. The resulting design approach is compared with field data, and effects of factors such as the direction of loading are discussed.

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Section: 5mentioning

confidence: 99%

Section: Shaft Frictionmentioning

confidence: 99%

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Design of driven piles in sand

Randolph

Dolwin²,

Beck³

1994

Géotechnique

257

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“…• Randolph (1994), Kulhawy (1984), Toolan et al (1990), Vesic (1967), Hettler (1982 and Kraft (1991) explained the trend of limiting values by K 0 depth profiles, friction fatigue processes, local shear-stress distributions and sand dilation;…”

Section: Fundamental Load Response Mechanisms and Property-based Designmentioning

confidence: 99%

“…• To allow for the degradation of friction due to pile length, Toolan et al (1990) presented a new method. Their aim was to account for the well-established observation that local shaft friction at any fixed level varies with pile penetration, as discussed by Vesic (1970), Hanna and Tan (1973), Lehane et al (1993).…”

Section: Fundamental Load Response Mechanisms and Property-based Designmentioning

confidence: 99%

Limit States Design (LSD) for Shallow and Deep Foundations

Foye¹,

Abou-Jaoude²,

Salgado³

2004

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IntroductionFoundation design consists of selecting and proportioning foundations in such a way that limit states are prevented. Limit states are of two types: Ultimate Limit States (ULS) and Serviceability Limit States (SLS). ULSs are associated with danger, involving such outcomes as structural collapse.SLSs are associated with impaired functionality, and in foundation design are often caused by excessive settlement. Reliability-based design (RBD) is a design philosophy that aims at keeping the probability of reaching limit states lower than some limiting value. Thus, a direct assessment of risk is possible with RBD. This evaluation is not possible with traditional working stress design. The use of RBD directly in projects is not straightforward and is cumbersome to designers, except in large-budget projects. Load and Resistance Factor Design (LRFD) shares most of the benefits of RBD while being much simpler to apply. LRFD has traditionally been used for ULS checks, but SLS's have been brought into the LRFD framework recently (AASHTO 1998).Load and Resistance Factor Design (LRFD) is a design method in which design loads are increased and design resistances are reduced through multiplication by factors that are greater than one and less than one, respectively. In this method, foundations are proportioned so that the factored loads are not greater than the factored resistances.In order for foundation design to be consistent with current structural design practice, the use of the same loads, load factors and load combinations would be required. In this study, we review the load factors presented in various LRFD Codes from the US, Canada and Europe. A simple first-order second moment (FOSM) reliability analysis is presented to determine appropriate ranges for the values of the load factors. These values are compared with those proposed in the Codes.For LRFD to gain acceptance in geotechnical engineering, a framework for the objective assessment of resistance factors is needed. Such a framework, based on reliability analysis is proposed in this study. Probability Density Functions (PDFs), representing design variable uncertainties, are required for analysis. A systematic approach to the selection of PDFs is presented.Such a procedure is a critical prerequisite to a rational probabilistic analysis in the development of LRFD methods in geotechnical engineering. Additionally, in order for LRFD to fulfill its promise for designs with more consistent reliability, the methods used to execute a design must be consistent with the methods assumed in the development of the LRFD factors. In this study, a methodology for the estimation of soil parameters for use in design equations is proposed that should allow for more statistical consistency in design inputs than is possible in traditional methods.The primary objective of this study is to propose a Limit States Design method for shallow and deep foundations that is based on a rational, probability-based investigation of design methods. FindingsThis research was able to deve...

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Shaft Resistance of Displacement Piles in Overconsolidated Cohesionless Soils

Alharthi

Hanna²

2018

Sustainability Issues for the Deep Foundations

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An Appraisal of API RP2A Recommendations for Determining Skin Friction of Piles in Sand

Cited by 24 publications

References 0 publications

Design of driven piles in sand

Design of driven piles in sand

Limit States Design (LSD) for Shallow and Deep Foundations

Shaft Resistance of Displacement Piles in Overconsolidated Cohesionless Soils

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