Response of fixed offshore platforms to wave and current loading including soil–structure interaction

Mostafa, Yasser E.; Naggar, M. Hesham El

doi:10.1016/j.soildyn.2003.11.008

Cited by 83 publications

(54 citation statements)

References 6 publications

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“…43 in table 3), when its fault normal component acts in the x-direction, in all load cases LC1-LC2-LC3. It is observed that the profiles in figure 9, with positive and negative deflections (the latter are slightly visible, for instance, in pile #1 of the Tripod), are in accordance with typical deflection profiles of flexible piles constrained by lateral springs and supporting structures under dynamic lateral loads [37]. For comparison, figure 9 also includes (i) the maxima lateral deflections due to wind-wave loads only (no earthquake loads), for the environmental states considered in load cases LC1-LC2-LC3; (ii) the lateral deflections at which the soil resistance forces attain, with a tolerance of 10 −2 , the maxima asymptotic values given by the p − y API curves [26] for the considered sandy soil [18,19], at various depths along the piles; note that these lateral deflections can be taken as indicators of a significant nonlinear soil response, because p − y curves deviate from linearity also for relatively small soil displacements [26].…”

Section: (A) Stress Resultant and Tower Top Acceleration Demands For supporting

confidence: 73%

“…Although a definitive answer as to whether earthquake loads are design driving for the two structures under study can be given only considering sitespecific conditions, these results substantiate the need for an accurate seismic assessment when installing offshore HAWTs in seismically active areas. In this context, refined seismic analyses should be carried out, considering vertical ground motion, variation of earthquake acceleration through soil layers [15], potential misalignment between wind and wave loads during earthquake shaking, and other important issues such as sensitivity to different models of p − y curves [37] and potential uncertainties in soil properties [39], alterations of the foundation stiffness due to on May 12, 2018 http://rsta.royalsocietypublishing.org/ Downloaded from…”

Section: Discussionmentioning

confidence: 99%

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Seismic analysis of offshore wind turbines on bottom-fixed support structures

Alati

Failla

Arena

2015

Phil. Trans. R. Soc. A.

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This study investigates the seismic response of a horizontal axis wind turbine on two bottom-fixed support structures for transitional water depths (30-60 m), a tripod and a jacket, both resting on pile foundations. Fully coupled, nonlinear time-domain simulations on full system models are carried out under combined wind-wave-earthquake loadings, for different load cases, considering fixed and flexible foundation models. It is shown that earthquake loading may cause a significant increase of stress resultant demands, even for moderate peak ground accelerations, and that fully coupled nonlinear time-domain simulations on full system models are essential to capture relevant information on the moment demand in the rotor blades, which cannot be predicted by analyses on simplified models allowed by existing standards. A comparison with some typical design load cases substantiates the need for an accurate seismic assessment in sites at risk from earthquakes.

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Section: (A) Stress Resultant and Tower Top Acceleration Demands For supporting

confidence: 73%

Section: Discussionmentioning

confidence: 99%

Seismic analysis of offshore wind turbines on bottom-fixed support structures

Alati

Failla

Arena

2015

Phil. Trans. R. Soc. A.

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“…The soil resistance to the pile movement is modeled using p-y curves, and t-z curves for lateral and axial loading, respectively. Static p-y curves for a single pile in sand can be established from the API guidelines: 25 (10) where p u is the ultimate resistance, (kN/m); is the effective soil unit weight, (kN/m 3 ); h is the depth, (m); and D is average pile diameter from surface to depth h, (m). C 1 , C 2 , and C 3 are coefficients determined from the API guidelines.…”

Section: P-y Model (P-y)mentioning

confidence: 99%

“…10 In this study, each pile is a 2.082 m outer diameter steel pile with spacing of 12 m center-to-center in the direction of loading. Therefore, S/D = 5.764, which is close to the group effect marginal value of 6.5 12 The p-multiplier for this spacing is determined using Eqs.…”

Section: Foundation Modelsmentioning

confidence: 99%

Soil-structure interaction on the response of jacket-type offshore wind turbine

Park

Chung

Shin

et al. 2015

Int. J. of Precis. Eng. and Manuf.-Green Tech.

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Jacket structures are still at the early stage of their development for use in the offshore wind industry. The aim of this paper is to investigate the effect of the soil-structure interaction on the response of an offshore wind turbine with a jacket-type foundation. For this purpose, two different models of flexible foundation-the p-y model and the p-y model considering pile groups effect-are employed to compare the dynamic responses with the fixed-base model. The modal analysis and the coupled dynamic analysis are carried out under deterministic and stochastic conditions. The influence of the soil-structure interaction on the response of the jacket foundation predicts that the flexible foundation model is necessary to estimate the loads of the offshore wind turbine structure well. It is suggested that during fatigue analysis the pile group effect should be considered for the jacket foundation.

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“…Mitwally and Novak [9] used a linear analysis to address dynamic interaction between pile-soil-pile, when the system is subjected to a random wave loading. Moreover, using the concept of dynamic p-y curves, the response of fixed offshore platforms to wave and current loading when taking into account the soil-pile interaction was investigated by Mostafa & Naggar [10].…”

Section: Introductionmentioning

confidence: 99%

Dynamic Response of an Offshore Pile, a Poro-Elastic Seabed and Seawater due to Water Waves

Lu¹,

Jeng²

2008

TOCIEJ

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Abstract:In this study, a coupled model is developed to address the dynamic response of an offshore pile to linear water waves. In the coupled model, the pile and the seabed are treated as a saturated poro-elastic medium described by Biot's dynamic theory, while the seawater is considered as a conventional acoustic medium. To establish the coupled model, boundary element formulations for saturated porous media are derived for the pile and the seabed, respectively, and the acoustic boundary element formulation is constructed for the seawater. The coupled boundary element model is obtained using these three boundary element formulations as well as the continuity conditions along the interfaces between the pile, the seabed and the seawater. In the model, linear water waves are considered as an external load and its load is evaluated via the wave function expansion method. Numerical results shows that increment of the modulus ratio between the pile and the seabed can reduce the horizontal displacement of the pile and the pore pressure of the seabed around the pile. Also, the maximum pore pressure of the seabed usually occurs at the upper part of the seabed around the pile.

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Response of fixed offshore platforms to wave and current loading including soil–structure interaction

Cited by 83 publications

References 6 publications

Seismic analysis of offshore wind turbines on bottom-fixed support structures

Seismic analysis of offshore wind turbines on bottom-fixed support structures

Soil-structure interaction on the response of jacket-type offshore wind turbine

Dynamic Response of an Offshore Pile, a Poro-Elastic Seabed and Seawater due to Water Waves

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