Dynamic response of a pile embedded into a layered soil

Martinelli, Mario; Burghignoli, A.; Callisto, Luigi

doi:10.1016/j.soildyn.2016.03.021

Cited by 27 publications

(10 citation statements)

References 23 publications

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“…Dynamic and nonlinear effects are of prominent importance in the ground response analysis, while the pile-soil kinematic interaction mechanism is of static and linear nature, as first discussed in Di Laora et al (2012) for homogeneous soils and confirmed further in Di Laora and Rovithis (2015) for nonhomogeneous soils. Similar findings on the efficiency of simplified elastic formulae to predict pile bending at the interface of two-layered soils by means of a ground response parameter were reported in Martinelli et al (2016) in which the nonlinear soil behavior was accounted for. With reference to experimental data, Chidichimo et al (2014) reproduced, with a nonlinear Winkler model, pile interface bending moments recorded from 1-g shaking tables.…”

Section: Problem Statement and Parametric Investigationsupporting

confidence: 78%

The Beneficial Role of Piles on the Seismic Loading of Structures

et al. 2019

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We examine the kinematic response of fixed-head vertical floating piles embedded in continuously nonhomogeneous soils and subjected to upward propagating seismic waves. The problem is explored numerically by means of a rigorous finite element (FE) model of the soil-pile system to quantify the kinematically induced reduction of the horizontal free-field spectral acceleration. Soil stiffness varies continuously with depth according to a generalized power law function. We show that kinematic pile response in the harmonic regime is controlled by a unique dimensionless frequency parameter involving the active pile length in a generalized nonhomogeneous soil. A new, simplified expression for the horizontal kinematic interaction factor Iu is proposed for practical time-domain applications while a novel physical interpretation of the filtering action of piles is reported by introducing the role of pile stiffness in averaging soil motion over an effective pile length. Following a parametric study under transient motion, we propose a set of novel, ready-to-use formulae for a rapid assessment of the pile-induced filtering action. An application of the proposed formulae to clayey soils is finally presented, leading to useful indications for the selection of the pile diameter associated with the maximum filtering potential.

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Section: Problem Statement and Parametric Investigationsupporting

confidence: 78%

The Beneficial Role of Piles on the Seismic Loading of Structures

et al. 2019

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“…With reference to the importance of nonlinear effects in the soil, the following are worthy of note: (1) material nonlinearity in the free field may have a dominant effect in controlling the value of shear wave propagation velocity V s and soil acceleration a s at the pile head; (2) as evident from Equation 31, soil stiffness has a minor effect in controlling the magnitude of kinematically induced stresses at the pile-soil interface. Accordingly, kinematically induced nonlinearity in the soil is typically minor, which can be understood given the small displacement mismatch between pile and soil under such conditions (see also Turner et al 2015, Martinelli et al 2016); (3) Equations 9 and 22 indicate that inertial bending moment at the pile head depends, respectively, on the fourth and fifth root of soil stiffness in homogeneous and inhomogeneous soil, so moment is not sensitive to stiffness degradation due to soil material nonlinearity. This observation is in contrast to pile head stiffness and associated displacements, which are sensitive to soil stiffness.…”

Section: Discussionmentioning

confidence: 99%

Size Limitations for Piles in Seismic Regions

Laora¹,

Mylonakis

Mandolini³

2017

Earthquake Spectra

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A novel theoretical study exploring the importance of pile diameter in resisting seismic actions of both the kinematic and the inertial type is reported. With reference to a pile under a restraining cap, it is shown analytically that for any given set of design parameters, a range of admissible pile diameters exists, bounded by a minimum and a maximum value above and below which the pile will yield at the top even with highest material quality and amount of reinforcement. The critical diameters depend mainly on seismicity, soil stiffness and safety factor against gravity loading, and to a lesser extent on structural strength. This scale effect is not present at interfaces separating soil layers of different stiffness, yet it may govern design at the pile head. The work at hand deals with both steel and concrete piles embedded in soils of uniform or increasing stiffness with depth. Closed-form solutions are derived for a number of cases, while others are treated numerically. Application examples and design issues are discussed.

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“…Note that due to the characteristics of the considered model, all the conclusions are only valid within the linear elasticity framework. However, previous works [8,46] remarked that soil material nonlinearity effects are negligible in kinematic soil-pile interaction (although they are dominant in the free field response), so the results of this study could still be applicable under such conditions. The obtained results confirm that the evolution-with-depth of the soil profile plays a major role on the maximum kinematic bending moments of pile foundations.…”

Section: Discussionmentioning

confidence: 83%

“…The effects of the soil profile characteristics on kinematic bending moments of pile foundations have received great attention during the last years. Especially, numerous research works [5,6,7,8,9,10,11,12,13,14,15] have focused on the problem of piles in soils that present several layers with sharply differing stiffness. In this particular case, critical kinematic bending moments are found around the layers interface, being sometimes larger that the ones present at the pile head.…”

Section: Introductionmentioning

confidence: 99%