Natural vibration frequency and damping of slender structures founded on monopiles

Zania, Varvara

doi:10.1016/j.soildyn.2014.01.007

Cited by 55 publications

(28 citation statements)

References 26 publications

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“…It must be mentioned that these springs are not only frequency dependent but also change with cycles of loading due to dynamic soil structure interaction. Further details on the dynamic interaction can be found in (Bhattacharya et al 2013b;Bhattacharya et al 2013c;Bhattacharya et al 2013a;Lombardi et al 2013;Zania 2014;Damgaard et al 2014) Randolph (1981), slender piles, both for homogeneous and linear inhomogeneous soils Table 3. Stiffness formulae by different researchers for rigid piles in various soil profiles.…”

Section: Foundation Stiffness Of Monopilesmentioning

confidence: 99%

Design of monopiles for offshore wind turbines in 10 steps

Arany

Bhattacharya

Macdonald

et al. 2017

Soil Dynamics and Earthquake Engineering

286

157

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ABSTRACT:A simplified design procedure for foundations of offshore wind turbines is often useful as it can provide the types and sizes of foundation required to carry out financial viability analysis of a project and can also be used for tender design. This paper presents a simplified way of carrying out the design of monopiles based on necessary data (i.e. the least amount of data), namely site characteristics (wind speed at reference height, wind turbulence intensity, water depth, wave height and wave period), turbine characteristics (rated power, rated wind speed, rotor diameter, cut-in and cut-out -upper limit of the 1P frequency range -fixed base (cantilever beam) natural frequency of the tower -characteristic yield strength -gravitational constant -distance from zero shear force location to pile toe -air gap between the highest expected wave crest level and the platform -wave number 0 -equivalent stiffness of first tower mode ℎ -horizontal modulus of subgrade reaction -total structural mass, also strain accumulation exponent 0 -equivalent mass of first tower mode -mass of the pile -mass of the rotor-nacelle assembly -mass of the tower -mass of the transition piece ℎ -horizontal coefficient of subgrade reaction ℎ1 -coefficient of subgrade reaction at the first load cycle ℎ -coefficient of subgrade reaction after N load cycles -shape parameter of Weibull distribution -undrained shear strength of soil , , -time, also degradation parameters degradation model -grout thickness -pile wall thickness -tower wall thickness -wall thickness of the transition piece -transition piece wall thickness -turbulent wind speed component -extreme gust speed ,

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Section: Foundation Stiffness Of Monopilesmentioning

confidence: 99%

Design of monopiles for offshore wind turbines in 10 steps

Arany

Bhattacharya

Macdonald

et al. 2017

Soil Dynamics and Earthquake Engineering

286

157

View full text Add to dashboard Cite

show abstract

“…Regarding the wind turbines, the interaction between their foundations (e.g., monopile systems, tripod and jacket structures, suction caissons as well as gravity‐based foundations,) and the surrounding soil media has been recently identified as a critical aspect for analysis and design purposes because it exerts severe influence on the dynamic behavior of these energy harnessing systems installed either inland or offshore (e.g.,). More specifically, both the mode shapes and the natural frequencies of a wind turbine may be changed because of the SSI, which also affects the overall system's damping depending mostly on the foundation properties and the height of the turbine . As a result, several researchers (e.g.,) have already introduced advanced approaches to account for the SSI effects in case of wind turbines, while their seismic behavior has been also found of high relevance with this dynamic interaction.…”

Section: Seismic Evaluation Of Wind Turbines Based On Numerical Simulmentioning

confidence: 99%

“…More specifically, both the mode shapes and the natural frequencies of a wind turbine may be changed because of the SSI, which also affects the overall system's damping depending mostly on the foundation properties and the height of the turbine. 123 As a result, several researchers (e.g., [124][125][126][127] ) have already introduced advanced approaches to account for the SSI effects in case of wind turbines, while their seismic behavior has been also found of high relevance with this dynamic interaction.…”

Section: Soil-structure Interaction Effects and Other Special Considementioning

confidence: 99%

Wind turbines and seismic hazard: a state-of-the-art review

2016

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Wind energy is a rapidly growing field of renewable energy and as such, intensive scientific and societal interest has been already attracted. Research on wind turbine structures has been mostly focused on the structural analysis, design and/or assessment of wind turbines mainly against normal (environmental) exposures while, so far, only marginal attention has been spent on considering extreme natural hazards that threat the reliability of the lifetime-oriented wind turbine's performance. Especially, recent installations of numerous wind turbines in earthquake prone areas worldwide (e.g., China, USA, India, Southern Europe and East Asia) highlight the necessity for thorough consideration of the seismic implications on these energy harnessing systems. Along these lines, this state-of-the-art paper presents a comparative survey of the published research relevant to the seismic analysis, design and assessment of wind turbines. Based on numerical simulation, either deterministic or probabilistic approaches are reviewed, since they have been adopted to investigate the sensitivity of wind turbines' structural capacity and reliability in earthquake-induced loading. The relevance of seismic hazard for wind turbines is further enlightened by available experimental studies, being also comprehensively reported through this paper. The main contribution of the study presented herein is to identify the key factors for wind turbines' seismic performance while important milestones for ongoing and future advancement are emphasized.

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“…The loss of perfect bonding between the soil and the foundation then significantly changes the dynamic properties of the foundation-structure system, an aspect typically disregarded in the design of foundations [11]. For instance, if the structural characteristics of the wind turbine, including the natural frequency and damping, are changed due to the detachment of the foundation, an unexpected and destructive vibration (resonance) may take place [12]. Hence, a rigorous investigation of the dynamic impedance of the embedded foundation under various contact conditions could markedly eliminate the uncertainty existent in its design.…”

Section: Introductionmentioning

confidence: 99%

Dynamic interaction of plates in an inhomogeneous transversely isotropic space weakened by a crack

et al. 2017

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The problem of axisymmetric vibration of a flat thin rigid circular plate located inside a vertically exponentially graded, transversely isotropic material of infinite extent is addressed by means of a displacement potential method. The contact condition on one side of the foundation is assumed to be the perfect adhesion with the media but known to be faced by a penny-shaped crack at the other side as it occurs in anchors. The mixed boundary value problem is formulated with the aid of Hankel integral transforms and is written in the form of a set of singular integral equations. The analytical procedure for the special case of vertical movement of the rigid plate results in a closed form solution. The solution is pursued numerically for the general elastodynamic case. The physical quantities, such as contact stress on the plate and the stress and displacement fields in the non-homogeneous medium are obtained for different materials.

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Natural vibration frequency and damping of slender structures founded on monopiles

Cited by 55 publications

References 26 publications

Design of monopiles for offshore wind turbines in 10 steps

Design of monopiles for offshore wind turbines in 10 steps

Wind turbines and seismic hazard: a state-of-the-art review

Dynamic interaction of plates in an inhomogeneous transversely isotropic space weakened by a crack

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