Elastic Stiffnesses of a Rigid Suction Caisson and Its Cylindrical Sidewall Shell

Efthymiou, Georgia; Gazetas, George

doi:10.1061/(asce)gt.1943-5606.0002013

Cited by 21 publications

(8 citation statements)

References 17 publications

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“…11 shows the computed global stiffness coefficients and the local stiffness coefficients for the skirt and base soil reactions of the monopile, relative to those of the caisson, for = 0 (homogeneous soil). This tendency is consistent with previous finite element studies described by Efthymiou & Gazetas (2018). It is evident from Fig.…”

Section: Application To Short Rigid Monopilessupporting

confidence: 93%

“…is considered also to be applicable to monopiles. This aspect of the paper draws on previous work by Efthymiou & Gazetas (2018) that indicates, on the basis of 3D finite element studies, that the influence of the lid on the overall stiffness of a caisson foundation becomes increasingly less significant as the embedment ratio is increased.…”

Section: Applications Of Oxcaissonmentioning

confidence: 99%

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A Winkler model for suction caisson foundations in homogeneous and non-homogeneous linear elastic soil

et al. 2022

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Suction caisson foundations provide options for new foundation systems for offshore structures, particularly for wind turbine applications. During the foundation design process, it is necessary to make reliable predictions of the stiffness of the foundation, since this has an important influence on the dynamic performance of the overall support structure. The dynamic characteristics of the structure, in turn, influence its fatigue life. This paper describes a thermodynamically consistent Winkler model, called OxCaisson, that delivers computationally efficient estimates of foundation stiffness for caissons installed in homogeneous and non-homogeneous linear elastic soil, for general six degrees-of-freedom loading. OxCaisson is capable of delivering stiffness predictions that are comparable to those computed with three-dimensional finite-element analysis, but at a much lower computational cost. Therefore, the proposed model is suited to design applications where both speed and accuracy are essential, such as large-scale fatigue assessments of offshore wind farm structures. The paper demonstrates that the OxCaisson model can also be applied to short, rigid monopile foundations.

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Section: Application To Short Rigid Monopilessupporting

confidence: 93%

Section: Applications Of Oxcaissonmentioning

confidence: 99%

A Winkler model for suction caisson foundations in homogeneous and non-homogeneous linear elastic soil

et al. 2022

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“…[Doherty et al, 2005] obtained the stiffnesses of rigid and flexible suction caissons for a few Poisson's ratios (ν = {0.2, 0.499}) and slendernesses (L/D = {0, 0.25, 0.5, 1.0, 2.0}), which come in the form of formulas and tables. More recently, [Efthymiou and Gazetas, 2018] obtained closed-form formulas for a flexible suction caisson with a fixed thickness, but their results are again limited up to L/D = 2. In the present paper, rigid cylindrical foundations with 0 ≤ L/D ≤ 6 embedded in a homogeneous half-space are assumed, and a new set of modified Gazetas-type formulas is proposed, see Appendix A.…”

Section: Methodsmentioning

confidence: 99%

Simple approach for including foundation–soil–foundation interaction in the static stiffnesses of multi-element shallow foundations

et al. 2021

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In common engineering practice, foundation-soil-foundation interaction of shallow foundations is frequently ignored. This is presumably due to cost/benefit reasons since computationally demanding finite and/or boundary element models are required for that purpose, and its effects are usually assumed as negligible. In this sense, the present paper provides a simple and inexpensive way of incorporating foundation-soil-foundation interaction through a numerically explicit stiffness matrix formulation. The necessary ingredients for homogeneous and non-homogeneous (shear modulus power-law variation with depth) half-spaces are given. The proposed approach is then applied to offshore wind turbines multiple suction caisson foundations (tripod and tetrapod), where it is observed that foundation-soilfoundation interaction is significant. Its range of validity is also established, and valuable ready-to-use closed-form formulas for the correction factors of the stiffnesses of tripod and tetrapod groups are also derived. The methodology is applicable as long as the spacing between foundations is somewhat greater than foundation depth.

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“…A number of studies have been carried out on the stiffnesses of suction caissons using a variety of numerical and analytical solutions (eg, Pais and Kausel; Doherty et al; Liingard et al; Gelagoti et al; He et al; Efthymiou and Gazetas). These studies have covered homogeneous and nonhomogeneous soil media and have included linear and nonlinear soil behavior.…”

Section: Introductionmentioning

confidence: 96%

Effect of foundation type and modelling on dynamic response and fatigue of offshore wind turbines

Løken

Kaynia

2019

Wind Energy

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This paper presents dynamic response and fatigue analyses of several bottom‐mounted offshore wind turbine (OWT) models, simulated in the aero‐hydro‐servo‐elastic simulation tool FAST. The distinction between the models is the foundations, which are modelled with different methods, concepts, and dimensions. The US National Renewable Energy Laboratory has developed a 5‐MW reference turbine supported on a monopile, the NREL 5MW, which was used as a reference model in this paper. The paper presents the implementation and comparison of two different foundation modeling methods, referred to as the simplified apparent fixity method and the improved apparent fixity method. Furthermore, sensitivity analyses of different monopile dimensions were performed, followed by sensitivity analyses of suction caisson foundations of different dimensions. The final part of the paper presents fatigue analyses for the foundation models considered in this study subjected to 17 load cases. Fatigue damage, fatigue life, and damage equivalent loads were calculated, as well as the relative fatigue contribution from each load case.

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Elastic Stiffnesses of a Rigid Suction Caisson and Its Cylindrical Sidewall Shell

Cited by 21 publications

References 17 publications

A Winkler model for suction caisson foundations in homogeneous and non-homogeneous linear elastic soil

A Winkler model for suction caisson foundations in homogeneous and non-homogeneous linear elastic soil

Simple approach for including foundation–soil–foundation interaction in the static stiffnesses of multi-element shallow foundations

Effect of foundation type and modelling on dynamic response and fatigue of offshore wind turbines

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