On time-domain uncoupled analyses for offshore wind turbines under seismic loads

Santangelo, Fabio; Failla, Giuseppe; Arena, Felice; Ruzzo, Carlo

doi:10.1007/s10518-017-0191-x

Cited by 23 publications

(21 citation statements)

References 23 publications

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“…Santangelo et al [38] compared the structural responses of coupled and uncoupled time-domain simulations for an offshore wind turbine under earthquake loadings. Kim et al [39] investigated the seismic fragility of a monopile offshore wind turbine by considering the SSI effect.…”

Section: Appropriate Accurate Reliablementioning

confidence: 99%

Investigation on the sensitivity of flexible foundation models of an offshore wind turbine under earthquake loadings

Yang

Bashir

et al. 2019

Engineering Structures

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This paper presents an investigation on the sensitivity of flexible foundation models of offshore wind turbines subjected to earthquake loadings. A novel seismic analysis framework (SAF) is developed and implemented in an open source aero-hydro-elastic analysis tool, "FAST", for accurately modelling the effects of seismic loadings on offshore wind turbines. SAF has been validated through comparisons against experimentally validated numerical tools, GH Bladed and NREL Seismic. The behaviours of three flexible foundation models, namely, the apparent fixity (AF), coupled springs (CS) and distributed springs (DS) methods, subjected to earthquake loadings have been examined in relation to a fixed foundation. A total of 224 fully coupled nonlinear simulations of the foundation models are performed using a dataset of 28 earthquake records which are scaled using the target spectrum matching technique to represent the actual seismic effects of the selected sites. The results reveal that the AF model appropriately reflects realistic situations in comparison to the CS model. In addition, the amplitudes of vibration induced by the earthquake loadings are larger for

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Section: Appropriate Accurate Reliablementioning

confidence: 99%

Investigation on the sensitivity of flexible foundation models of an offshore wind turbine under earthquake loadings

Yang

Bashir

et al. 2019

Engineering Structures

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“…In performing the analysis of dynamic responses of wind turbines subjected to wind loads and further excited by ground motion corresponding to the earthquake, a seismic module was added in GH Bladed [6]. With the use of GH Bladed, Santangelo et al [25][26] conducted a set of time-domain simulations for the wind turbine under multiple loadings. The differences between the results of fullycoupled and uncoupled time-domain simulations were investigated.…”

Section: Introductionmentioning

confidence: 99%

Analysis of seismic behaviour of an offshore wind turbine with a flexible foundation

Yang

Bashir

et al. 2019

Ocean Engineering

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Analysis of seismic behaviour of an offshore wind turbine with a flexible foundation http://researchonline.ljmu.ac.uk/id/eprint/10382/ Article LJMU has developed LJMU Research Online for users to access the research output of the University more effectively. , J (2019) Analysis of seismic behaviour of an offshore wind turbine with a flexible foundation. Ocean Engineering, 178. pp. 215-228. Abstract: This paper investigates the effects of nonlinear soil behaviours on the structural responses of offshore wind turbines (OWTs) subjected to wind, wave and earthquake loadings. A novel seismic analysis framework (SAF) is developed for the assessment of seismic behaviours of OWTs with flexible and fixed foundations. The SAF consists of an improved QuakeDyn module that is implemented into an open source tool (FAST). SAF has been validated through benchmark studies using numerical tools and the results show good agreements. Fully coupled nonlinear simulations have been performed for OWTs with fixed and flexible foundations under operational, parked and emergency shutdown states. The flexible foundation is modelled using nonlinear p-y curves obtained using LPILE. For all the examined operating conditions, notable differences of magnitude and variation in the responses between the flexible and fixed cases are observed, indicating the need for soil effects to be accounted in seismic behaviour analysis of wind turbines. It is further observed that the earthquake induces more severe vibrations on wind turbines with a flexible foundation compared to the one with a fixed base. Also, aerodynamic damping dissipates more energy from earthquake excitation resulting in a smaller tower-top fore-aft displacement. The shutdown triggered by the earthquake causes a 34% increase in the mudline bending moment for the flexible foundation case, while a decreasing trend is observed for the fixed foundation model. Similar observations are made  Corresponding author: lichun_usst@163.com 2 / 41regarding the tower-top displacements. The observations imply that ignoring the soil effect may lead to misjudgement of the consequence of an emergency shutdown. The relative orientation of the ground motion with respect to the wind direction causes significant difference in the seismic behaviour of the wind turbine. This confirms that it is necessary to interchange the horizontal components of an earthquake in order to consider the intersectional effect between ground motion and wind.

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“…To eliminate the influence of earthquake forces in the SS direction, one of the two horizontal components of earthquakes which will cause larger a tower-base bending moment is selected as the input ground motion and applied along the FA direction of the wind turbine. The studies conducted by Santangelo et al [31][32][33] indicated that the error between the coupled and uncoupled methods was related to earthquakes. Consequently, a set of earthquakes shown in Table 3 are selected from the database of Pacific Earthquake Engineering Research center (PEER) to evaluate the uncoupled model thoroughly, where the far field and near field records recommended by Federal Emergency Management Agency (FEMA) [42] are included.…”

Section: Earthquake Loadmentioning

confidence: 99%

“…This method was initially used to evaluate the seismic fragility of the NREL 5 MW wind turbine for different mean wind speeds. Immediately, this method was implemented in the GH BLADED software and assessed by comparisons between the coupled and uncoupled analysis results [31][32][33]. Besides, the uncoupled analysis was also performed in ABAQUS where aerodynamic loading was computed by the BEM theory and the average pitch angle was used to consider the effect of pitch regulation [34,35].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of an Uncoupled Method for Analyzing the Seismic Response of Wind Turbines Excited by Wind and Earthquake Loads

Wang

et al. 2020

Energies

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There is a significant interaction between wind and earthquakes for large-scaled wind turbines due to an aeroelastic effect. This study evaluates the accuracy of an uncoupled method extensively utilized to analyze the seismic response of wind turbines at the operational state. Initially, the oscillation of the blade for the National Renewable Energy Laboratory (NREL) 5 MW wind turbine excited by wind and wind-earthquake combination, respectively, is compared using the fully coupled method to verify the assumption in this uncoupled method. Subsequently, the influence of ground motions on the aerodynamic loadings of the rotor is discussed to evaluate the interaction between wind and earthquake loads. In addition, the accuracy of the uncoupled method is assessed by comparing the analysis results of the coupled and uncoupled methods, where different mean wind speed and equivalent aerodynamic damping ratio are considered. The results indicate that the oscillation velocity of blades and thrust on the rotor are significantly influenced by ground motions. Moreover, the amplitude of thrust variations caused by earthquakes increases monotonously with the oscillation velocity amplitude of blade-root. The errors between the two models are beyond the engineering margins for some earthquakes, such that it is difficult to optimize a consistent aerodynamic damping in the uncoupled model to accurately predict the seismic response of wind turbines.

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On time-domain uncoupled analyses for offshore wind turbines under seismic loads

Cited by 23 publications

References 23 publications

Investigation on the sensitivity of flexible foundation models of an offshore wind turbine under earthquake loadings

Investigation on the sensitivity of flexible foundation models of an offshore wind turbine under earthquake loadings

Analysis of seismic behaviour of an offshore wind turbine with a flexible foundation

Evaluation of an Uncoupled Method for Analyzing the Seismic Response of Wind Turbines Excited by Wind and Earthquake Loads

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