Kinematic Bending of Fixed-Head Piles in Nonhomogeneous Soil

Karatzia, Xenia; Mylonakis, George

doi:10.1061/(asce)gt.1943-5606.0001270

Cited by 78 publications

(56 citation statements)

References 29 publications

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“…e superstructure is simulated by beam, pipe, and mass elements, whereas the raft, piles, and soil are modeled with solid elements (continuum elements). During the simulation of the soil medium, to reduce the effect of boundary conditions on the dynamic response of the system, the lateral model boundary is chosen as approximately 4 times the lateral size of the raft in the x and y directions [32], and the bottom of which is 5 m below the top of the bedrock. e final size of the 3D soil model is set as 322 m × 223 m × 53 m, as shown in Figure 5.…”

Section: Modeling Of the Soil-pile-structurementioning

confidence: 99%

Influence of Variable Rigidity Design of Piled Raft Foundation on Seismic Performance of Buildings

Xie

Chi

Wang

2020

Mathematical Problems in Engineering

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In order to reduce the costs and improve the overall performance of building systems, the static optimized design with variable rigidity of piled raft foundations has been widely used in recent years. Variable rigidity design of piled raft foundations that support midrise buildings in high-risk seismic zones can alter the dynamic characteristics of the soil-pile-structure system during an earthquake due to soil-pile-structure interaction. To investigate these aspects, a nuclear power plant sitting on multilayered soil is simulated numerically. e paper describes a numerical modeling technique for the simulation of complex seismic soil-pile-structure interaction phenomena. It was observed that the total shear force on top of the piles and the rocking of the raft are reduced after optimization, whereas the displacement of the superstructure is nearly unaffected. e findings of this study can help engineers select a correct pile arrangement when considering the seismic performance of a building sitting on soft soil.

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Section: Modeling Of the Soil-pile-structurementioning

confidence: 99%

Influence of Variable Rigidity Design of Piled Raft Foundation on Seismic Performance of Buildings

Xie

Chi

Wang

2020

Mathematical Problems in Engineering

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“…Perfect contact (ie, no gap nor slippage) is considered at the soil‐pile interface. The soil layer of thickness H (= L ) is described by a constant Poisson ratio ν s and a depth‐varying shear modulus G s ( z ) ( z being the vertical coordinate) expressed by the following power‐law function

G_{s} false(z false) = G_{s H} {([], b + false(1 - b false) ((), \frac{z}{H}))}^{n}

and

b = {((), \frac{G_{s 0}}{G_{s H}})}^{1 false/ n},

where G s H corresponds to the soil shear modulus at the base of the layer ( z = H ) and n and b are dimensionless inhomogeneity parameters. It is evident that b = 0 corresponds to zero stiffness at the soil surface and b = 1 (or n = 0) to constant stiffness along the thickness of the layer (eg, a heavily over‐consolidated clay).…”

Section: Proposed Analytical Modelmentioning

confidence: 99%

An analytical continuum model for axially loaded end‐bearing piles in inhomogeneous soil

Anoyatis

Mylonakis

Tsikas³

2019

Num Anal Meth Geomechanics

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Summary An approximate static solution is derived for the elastic settlement and load‐transfer mechanism in axially loaded end‐bearing piles in inhomogeneous soil obeying a power law variation in shear modulus with depth. The proposed generalised formulation can handle different types of soil inhomogeneity by employing pertinent eigenexpansions of the dependent variables over the vertical coordinate, in the form of static soil “modes”, analogous to those used in structural dynamics. Contrary to available models for homogeneous soil, the associated Fourier coefficients are coupled, obtained as solutions to a set of simultaneous algebraic equations of equal rank to the number of modes considered. Closed‐form solutions are derived for the (1) pile head stiffness; (2) pile settlement, axial stress, and side friction profiles leading to actual, depth‐dependent Winkler moduli, (3) displacement and stress fields in the soil; and (4) average, depth‐independent Winkler moduli to match pile head settlement. The predictive power of the model is verified via comparisons against finite element analyses. The applicability to inhomogeneous soil of an existing regression formula for the average Winkler modulus is explored.

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“…Formulas are derived for idealised soil conditions, and the application to inhomogeneous soils generally requires an engineering judgement, based on equivalence criteria in terms of parameters adopted to describe the non‐dimensional problem. (eg, Laora and Rovithis and Karatzia and Mylonakis).…”

Section: Formulas For Estimating Lpm Parametersmentioning

confidence: 99%

A lumped parameter model for time‐domain inertial soil‐structure interaction analysis of structures on pile foundations

Carbonari

Morici

Dezi

et al. 2018

Earthq Engng Struct Dyn

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Summary The paper presents a lumped parameter model for the approximation of the frequency‐dependent dynamic stiffness of pile group foundations. The model can be implemented in commercial software to perform linear or nonlinear dynamic analyses of structures founded on piles taking into account the frequency‐dependent coupled roto‐translational, vertical, and torsional behaviour of the soil‐foundation system. Closed‐form formulas for estimating parameters of the model are proposed with reference to pile groups embedded in homogeneous soil deposits. These are calibrated with a nonlinear least square procedure, based on data provided by an extensive non‐dimensional parametric analysis performed with a model previously developed by the authors. Pile groups with square layout and different number of piles embedded in soft and stiff soils are considered. Formulas are overall well capable to reproduce parameters of the proposed lumped system that can be straightforwardly incorporated into inertial structural analyses to account for the dynamic behaviour of the soil‐foundation system. Some applications on typical bridge piers are finally presented to show examples of practical use of the proposed model. Results demonstrate the capability of the proposed lumped system as well as the formulas efficiency in approximating impedances of pile groups and the relevant effect on the response of the superstructure.

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Kinematic Bending of Fixed-Head Piles in Nonhomogeneous Soil

Cited by 78 publications

References 29 publications

Influence of Variable Rigidity Design of Piled Raft Foundation on Seismic Performance of Buildings

Influence of Variable Rigidity Design of Piled Raft Foundation on Seismic Performance of Buildings

An analytical continuum model for axially loaded end‐bearing piles in inhomogeneous soil

A lumped parameter model for time‐domain inertial soil‐structure interaction analysis of structures on pile foundations

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