Dynamic Models of Piled Foundations

2013 ◽  
Vol 65 (3) ◽  
Author(s):  
Kirsty A. Kuo ◽  
Hugh E. M. Hunt
Keyword(s):  
Earthquake Engineering ◽  
Dynamic Models ◽  
Offshore Structures ◽  
Boundary Element Methods ◽  
Structure Theory ◽  
Winkler Foundation ◽  
Pile Groups ◽  
Foundation Design ◽  
Interaction Factors ◽  
Piled Foundations

The vibration behavior of piled foundations is an important consideration in fields such as earthquake engineering, construction, machine-foundation design, offshore structures, nuclear energy, and road and rail development. This paper presents a review of the past 40 years' literature on modeling the frequency-dependent behavior of pile foundations. Beginning with the earliest model of a single pile, adapted from those for embedded footings, it charts the development of the four pile-modeling techniques: the “dynamic Winkler-foundation” approach that uses springs to represent the effect of the soil; elastic-continuum-type formulations involving the analytical solutions for displacements due to a subsurface disk, cylinder, or other element; boundary element methods; and dynamic finite-element formulations with special nonreflecting boundaries. The modeling of pile groups involves accounting for pile-soil-pile interactions, and four such methods exist: interaction factors; complete pile models; the equivalent pier method; and periodic structure theory. Approaches for validating pile models are also explored.

Cyclic axial behaviour of piles and pile groups in sand

2012 ◽  
Vol 49 (9) ◽  
pp. 1074-1087 ◽  
Author(s):  
Zheming Li ◽  
Malcolm D. Bolton ◽  
Stuart K. Haigh
Keyword(s):  
Axial Load ◽  
Pile Group ◽  
Offshore Structures ◽  
Pile Groups ◽  
Axial Loads ◽  
Bored Pile ◽  
Load Cycling ◽  
Permanent Settlement ◽  
Number Of Cycles ◽  
Piled Foundations

Piled foundations are often subjected to cyclic axial loads. This is particularly true for the piles of offshore structures, which are subjected to rocking motions caused by wind or wave actions, and for those of transport structures, which are subjected to traffic loads. As a result of these cyclic loads, excessive differential or absolute settlements may be induced during the piles’ service life. In the research presented here, centrifuge modelling of single piles and pile groups was conducted to investigate the influence of cyclic axial loads on the performance of piled foundations. The influence of installation method was investigated and it was found that the cyclic response of a pile whose jacked installation was modelled correctly is much stiffer than that of a bored pile. During displacement-controlled axial load cycling, the pile head stiffness reduces with an increasing number of cycles, but at a decreasing rate; during force-controlled axial load cycling, more permanent settlement is accumulated for a bored pile than for a jacked pile. The performance of individual piles in a pile group subjected to cyclic axial loads is similar to that of a single pile, without any evident group effect. Finally, a numerical analysis of axially loaded piles was validated by centrifuge test results. Cyclic stiffness of soil at the base of pre-jacked piles increases dramatically, while at base of jacked piles it remains almost constant.

scholarly journals Development of Simulation Based p-Multipliers for Laterally Loaded Pile Groups in Granular Soil Using 3D Nonlinear Finite Element Model

2020 ◽  
Vol 11 (1) ◽  
pp. 26
Author(s):  
Muhammad Bilal Adeel ◽  
Muhammad Asad Jan ◽  
Muhammad Aaqib ◽  
Duhee Park
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Design Guidelines ◽  
American Petroleum Institute ◽  
Winkler Foundation ◽  
Group Effect ◽  
Pile Groups ◽  
Element Analysis ◽  
Laterally Loaded Pile ◽  
Laterally Loaded

The behavior of laterally loaded pile groups is usually accessed by beam-on-nonlinear-Winkler-foundation (BNWF) approach employing various forms of empirically derived p-y curves and p-multipliers. Averaged p-multiplier for a particular pile group is termed as the group effect parameter. In practice, the p-y curve presented by the American Petroleum Institute (API) is most often utilized for piles in granular soils, although its shortcomings are recognized. In this study, we performed 3D finite element analysis to develop p-multipliers and group effect parameters for 3 × 3 to 5 × 5 vertically squared pile groups. The effect of the ratio of spacing to pile diameter (S/D), number of group piles, varying friction angle (φ), and pile fixity conditions on p-multipliers and group effect parameters are evaluated and quantified. Based on the simulation outcomes, a new functional form to calculate p-multipliers is proposed for pile groups. Extensive comparisons with the experimental measurements reveal that the calculated p-multipliers and group effect parameters are within the recorded range. Comparisons with two design guidelines which do not account for the pile fixity condition demonstrate that they overestimate the p-multipliers for fixed-head condition.

scholarly journals Uptake and Dissemination of Multi-Criteria Decision Support Methods in Civil Engineering—Lessons from the Literature

2021 ◽  
Vol 11 (7) ◽  
pp. 2940
Author(s):  
Michael Bruen
Keyword(s):  
Geographical Distribution ◽  
Earthquake Engineering ◽  
Civil Engineering ◽  
Full Range ◽  
Sewage Treatment ◽  
Foundation Design ◽  
Analytic Hierarchy ◽  
Design Earthquake ◽  
Support Methods ◽  
Hierarchy Process

The SCOPUS and Wed of Science bibliometric databases were searched for papers related to the use of multi-criteria methods in civil engineering related disciplines. The results were analyzed for information on the reported geographical distribution of usage, the methods used, the application areas with most usage and the software tools used. There was a wide geographical distribution of usage with all northern hemisphere continents well represented. However, of the very many methods available, a small number seemed to dominate usage, with the Analytic Hierarchy Process being the most frequently used. The application areas represented in the documents found was not widely spread and mainly seemed to be focused on issues such as sustainability, environment, risk, safety and to some extent project management, with less usage on other areas. This may be due to individual engineer’s choices in relation to if and how to disseminate the results of their work and to their choice of keywords and titles that determine if their publications are selected in bibliographic searches and thus more visible to a wider readership. A comparison with more topic focused searches, relating to Bridge Design, Earthquake Engineering, Cladding, Sewage Treatment, Foundation design, Truss design, Water Supply, Building Energy, Route selection and Transport mode showed very different results. Analysis of the papers in this area indicated that the full range of supporting software available for multi-criteria decision analysis (many listed in this paper) may not be fully appreciated by potential users.

scholarly journals Flexible Pile Group Interaction Factors under Arbitrary Lateral Loading in Sand

2020 ◽  
Vol 8 (10) ◽  
pp. 800
Author(s):  
Miloš Marjanović ◽  
Mirjana Vukićević ◽  
Diethard König
Keyword(s):  
Numerical Study ◽  
Group Interaction ◽  
Pile Group ◽  
Lateral Loading ◽  
Soil Conditions ◽  
Offshore Platforms ◽  
Lateral Loads ◽  
Pile Groups ◽  
Main Hypothesis ◽  
Interaction Factors

Marine and harbor structures, wind turbines, bridges, offshore platforms, industrial chimneys, retaining structures etc. can be subjected to significant lateral loads from various sources. Appropriate assessment of the foundations capacity of these structures is thus necessary, especially when these structures are supported by pile groups. The pile group interaction effects under lateral loading have been investigated intensively in past decades, and the most of the conducted studies have considered lateral loading that acts along one of the two orthogonal directions, parallel to the edge of pile group. However, because of the stochastic nature of its source, the horizontal loading on the pile group may have arbitrary direction. The number of studies dealing with the pile groups under arbitrary loading is very limited. The aim of this paper is to investigate the influence of the arbitrary lateral loading on the pile group response, in order to improve (extend) the current design approach for laterally loaded pile groups. Free head, flexible bored piles in sand were analyzed through the extensive numerical study. The main hypothesis of the research is that some critical pile group configurations, loading directions, and soil conditions exist, which can lead to the unsafe structural design. Critical pile positions inside the commonly used pile group configurations are identified with respect to loading directions. The influence of different soil conditions was discussed.

scholarly journals Editorial: Advanced research on offshore structures and foundation design: part 1

2019 ◽  
Vol 172 (4) ◽  
pp. 118-123 ◽  
Author(s):  
T. Fazeres-Ferradosa ◽  
P. Rosa-Santos ◽  
F. Taveira-Pinto ◽  
E. Vanem ◽  
H. Carvalho ◽  
...  
Keyword(s):  
Offshore Structures ◽  
Foundation Design

Beam-on-Nonlinear-Winkler-Foundation Modeling of Shallow, Rocking-Dominated Footings

2009 ◽  
Vol 25 (2) ◽  
pp. 277-300 ◽  
Author(s):  
Chad W. Harden ◽  
Tara C. Hutchinson
Keyword(s):  
Earthquake Engineering ◽  
Energy Content ◽  
Nonlinear Behavior ◽  
Seismic Energy ◽  
Shallow Foundation ◽  
Winkler Foundation ◽  
Soil Foundation ◽  
Performance Based Earthquake Engineering ◽  
Foundation Structure ◽  
Selection Of

The nonlinear behavior of shallow foundations under large amplitude earthquake-induced loading can result in dissipation of seismic energy through the mechanism of soil yielding beneath the foundation. In addition, foundation uplifting may shift the period of the soil-foundation-structure system away from the damaging energy content of most earthquakes. However, this yielding and uplifting may lead to excessive transient and permanent deformations (settlement, rocking, and sliding). Therefore, modeling procedures that account for foundation nonlinearity and uplift are needed before these benefits can be realized in performance based earthquake engineering (PBEE) practice. This paper adopts a beam-on-nonlinear-Winkler-foundation (BNWF) simulation methodology for modeling shallow foundation-structure systems, where seismically-induced rocking plays a predominant role in their response. Numerical results demonstrate that reasonable comparison between the nonlinear Winkler-based approach, and experimental response in terms of moment-rotation, settlement-rotation, and shear-sliding displacement can be obtained, given an appropriate selection of model and soil properties.

Nonlinear vibration of pile groups under lateral loading

1992 ◽  
Vol 29 (4) ◽  
pp. 702-710 ◽  
Author(s):  
Hans H. Vaziri ◽  
Yingcai Han
Keyword(s):  
Dynamic Response ◽  
Nonlinear Vibration ◽  
Damping Ratio ◽  
Pile Group ◽  
Harmonic Excitation ◽  
Pile Groups ◽  
Plane Normal ◽  
Interaction Factors ◽  
Full Scale Tests ◽  
Measured Response

Dynamic response of a pile group, comprising six full-size cast-in-place reinforced concrete piles, is investigated under varying levels of lateral harmonic excitation in two directions: along a plane composed of three piles (X-direction) and along a plane normal to it composed of two piles (Y-direction). The measured response is compared with the theoretical predictions using the dynamic interaction factors approach. To account for the nonlinear response of the pile group using the theoretical model, provisions are made for yielding of soil around the piles by introducing the boundary-zone concept. It is shown that the proposed theory adequately captures the measured response of the pile group under both linear (weak excitation) and nonlinear (strong excitation) conditions. The study performed indicates that although the rocking stiffness of the pile group is strongly influenced by the number of piles along the direction of excitation, the horizontal stiffness remains virtually unaffected. The results obtained show that the stiffness and damping ratio of the pile group reduce as the excitation intensity increases. It is also found that the pile–soil–pile interaction plays a major role in the overall dynamic response of the pile group; this effect is manifested by a reduction in the stiffness and an increase in the damping of the pile group. Key words : dynamics, vibration, piles, pile group, nonlinear vibration, full-scale tests, modelling, resonance, soil separation, soil yielding.

scholarly journals Investigating the Effect of Distance and Diameter Ratio of Elliptical Piles on the Amount of Force Exerted by Waves in the Pile Groups with Regular Layout

2018 ◽  
Vol 8 (1) ◽  
pp. 37-46
Author(s):  
M. Ghatarband ◽  
M. Behdarvandi Askar
Keyword(s):  
Numerical Modeling ◽  
Safety Factor ◽  
Pile Group ◽  
Offshore Structures ◽  
Diameter Ratio ◽  
Pile Groups ◽  
Distance Ratio ◽  
Offshore Area

Abstract Today, advanced countries compete enormously for further exploitation in the offshore area, for its enormous fresh resources and space. Therefore, these competitions will double the importance of these types of structures. As it is known, the most important part in the design of the offshore structures is the design of the piles on which the structure will be placed. Engineers have always been trying to build these types of structures with the least cost and the highest safety factor. In this research, the effect of distance and the ratio of the elliptical pile diameters on the strength of the pile group was evaluated using numerical modeling. Five different states of diameter ratios including: 1.2, 1.4, 2, 2.5, 3 and five different distance ratios were investigated. The results demonstrate that with the increase in the diameter ratio, the amount of force decreases while it increases as the distance ratio rises.

The bearing capacity of rigid piles and pile groups under inclined loads in clay

1981 ◽  
Vol 18 (2) ◽  
pp. 297-300 ◽  
Author(s):  
G. G. Meyerhof
Keyword(s):  
Bearing Capacity ◽  
Ultimate Bearing Capacity ◽  
Test Results ◽  
Pile Groups ◽  
Free Standing ◽  
Previous Theory ◽  
Inclined Loads ◽  
Load Tests ◽  
Batter Piles ◽  
Piled Foundations

The ultimate bearing capacity of rigid vertical and batter piles and pile groups in clay has been determined under various inclinations of the load, varying from the vertical to horizontal directions. The results of load tests on single model piles of different lengths and inclinations and on free-standing groups and piled foundations are compared with theoretical estimates. The influence of load inclination on the bearing capacity can be represented by simple interaction relationships between the axial and normal components of the ultimate load. The effect of eccentricity of the load on the ultimate bearing capacity of pile groups is discussed on the basis of previous theory and model test results.

scholarly journals Numerical modeling of the seismic performance of monopile supported wind turbines in sandy soils susceptible to liquefaction.

2018 ◽  
Vol 7 (2.13) ◽  
pp. 263
Author(s):  
Mehran Tirandazian ◽  
Gholamreza Nouri
Keyword(s):  
Wind Turbines ◽  
Computational Cost ◽  
Wind Farms ◽  
Bottom Layer ◽  
Offshore Structures ◽  
Offshore Wind ◽  
Elastic Response ◽  
Winkler Foundation ◽  
Elastic Response Spectra ◽  
Soil Layering

Since 1980, as wind farms have moved from coastal to offshore areas, the wind energy industry has been completely transformed which in turn has led to the increase in the construction of wind turbines. On the other hand, harsher offshore environmental conditions have led to larger lateral loads and anchorages applied to the wind turbines and specifically to their piles than other coastal and offshore structures. Thus, more solid piles are required to ensure proper rigidity and bearing capacity. Liquefaction is one of the most important seismic hazards through which various damages caused to different parts of wind turbines. In order to develop coastal and offshore structures in Iran, a study of liquefaction is of great importance due in part to the high risk of seismicity. In this study, the effect of liquefaction on seismic response of offshore wind turbines is examined taking advantage of a finite element model. To this end, all analyzes have been carried out in both occurrence and non-occurrence of the liquefaction, so that by comparing these two modes, the mechanisms affecting the seismic behavior of wind turbines are understood. As depth increases, the possibility of liquefaction is reduced due to higher pressure. Liquefaction is considered to a depth of 20 m and structural behavior is evaluated based on the level of seismic hazard, the thickness of the susceptible layers, soil compaction, the non-fluidizing top layer, the gradient of the earth, the thickness of the monopole, the dimensions of the wind turbine and different soil layering conditions. According to the mentioned factors, a comprehensive and parametric study of the behavior of wind turbines in seismic zones, and in different loading conditions, pile diameters and soil layering is carried out in soils prone to liquefaction. Since analyzes are performed in both occurrence and non-occurrence of the liquefaction, the number of analyzes and computational cost in this research becomes enormous. Therefore, there is a need for a highly effective software and a practical modeling method that will allow for this comprehensive study. Open Sees software and beam on nonlinear Winkler foundation approach are used to model the soil-pile-structure interaction. The minor differences observed in the laboratory values compared to the numerically calculated ones may refer to the fact that the chamber is not modeled. In the bottom layer, as the depth decreases, the elastic response spectra record larger values which are due to the resonance in the structure.  

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