Development of Seismic Demand for Chang-Bin Offshore Wind Farm in Taiwan Strait

Wang, Yukai; Chai, Juin Fu; Chang, Yu Wen; Huang, Ti Ying; Kuo, Yao‐Lung

doi:10.3390/en9121036

Cited by 12 publications

(7 citation statements)

References 6 publications

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“…Many attempts to study the seismic dynamic responses [6][7][8][9], structural safety [4,5,[10][11][12] and analytical methods [4,13] of wind turbines have been conducted. Most studies focused on onshore wind turbines, which are shorter in the cantilever length than their offshore counterparts.…”

Section: Introductionmentioning

confidence: 99%

Seismic Fragility Analysis of Monopile Offshore Wind Turbines under Different Operational Conditions

Kang

et al. 2017

Energies

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Offshore wind turbines in seismic active areas suffer from earthquake impacts. In this study, seismic fragility analysis of a monopile offshore wind turbine considering different operational conditions was performed. A finite element model for a 5 MW monopile offshore wind turbine was developed using the OpenSees platform. The interaction between the monopile and the seabed soil was modeled as a beam-on-nonlinear-winkler-foundation (BNWF). A nonlinear time history truncated incremental dynamic analysis (TIDA) was conducted to obtain seismic responses and engineering demand parameters. Potential damage states (DSs) were defined as excessive displacement at the nacelle, rotation at the tower top, and the allowable and yield stresses at the transition piece. Fragility curves were plotted to assess the probability of exceeding different damage states. It was found that seismic responses of the wind turbine are considerably influenced by environmental wind and wave loads. Subject to earthquake motions, wind turbines in normal operation at the rated wind speed experience higher levels of probability of exceeding damage states than those in other operational conditions, i.e., in idling or operating at higher or lower wind speed conditions.

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Section: Introductionmentioning

confidence: 99%

Seismic Fragility Analysis of Monopile Offshore Wind Turbines under Different Operational Conditions

Kang

et al. 2017

Energies

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“…The effective unit weight of soil is 8.5-9.6 kN/m 3 . Table 1 presents the simplified soil layers for simulation [25]. Table 2 and Figure 2 show the dimensions and other fundamental information about the met mast.…”

Section: Met Mast Of Tpc In the Chang-bin Offshore Wind Farmmentioning

confidence: 99%

Effect of Scour on the Natural Frequency Responses of the Meteorological Mast in the Taiwan Strait

Tseng¹,

Kuo²,

Lu³

et al. 2018

Energies

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The meteorological mast (met mast) for the Taiwan Power Company's offshore wind farm is located in Taiwan Strait near Changhua County. The p-y curve method recommended in the current offshore foundation design codes does not account for the local scour around the pile foundation; it overestimates the lateral pile deformation and underestimates the foundation stiffness. This paper presents a method to correct the initial modulus of subgrade reaction and modify the ultimate lateral resistance caused by the local scour. The natural frequency of the met mast structure is also determined by a numerical model and verified with the measured data in situ. A comprehensive parameter study is performed to analyze the effect of scour on the dynamic responses of the met mast. Two types of foundation model, a coupled-springs foundation model and a distributed-springs foundation model, are considered in the dynamic analysis of the met mast. The results demonstrate that using a distributed-springs foundation model provides a relatively accurate estimate of the natural frequencies of the met mast structure. Furthermore, the scour exerted significant effects on certain modes of the vibration responses. The natural frequencies of the met mast structure can be reduced by approximately 14% due to scour, particularly in the horizontal bending modes. This paper also provides a preliminary strategy for structural monitoring and analysis to detect scour damage on offshore wind turbines with monopile foundations.

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“…The effective unit weight of sand was 9.61-10.58 kN/m 3 . Figure 9 and Tables 2 and 3 show relevant soil data [41] …”

Section: Reference Offshore Wind Turbine Of National Renewable Energymentioning

confidence: 99%

An Investigation into the Effect of Scour on the Loading and Deformation Responses of Monopile Foundations

2017

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Severe foundation scour may occur around monopile foundations of offshore wind turbines due to currents and waves. The so-called p-y curves method is suggested in the existing design recommendations to determine the behavior of monopiles unprotected against scour and the reduction of effective soil stress is accounted for by the extreme scour depth. This conservative design approach does not consider the geometry of the scour hole and the effect of pile diameter on the soil resistance. An underestimated foundation stiffness would be obtained, thereby influencing the predicted overall response of the support structure of an offshore wind turbine. In this study, we calculated the load-deformation response and foundation stiffness of a monopile when scour occurred. The influence of pile diameter on the initial modulus of subgrade reaction, and the modification of the ultimate soil resistance of a monopile subject to scour are evaluated. The commercial software BLADED was used to simulate the dynamic response of the reference offshore wind turbine with monopile unprotected against scour at Chang-Bin offshore wind farm in Taiwan Strait. The results showed that when the p-y curve suggested by existing design regulation was used to calculate the load-deformation response, the foundation stiffness was underestimated where the scour depth was greater than the pile diameter, but the foundation stiffness was overestimated when the scour depth was less than the pile diameter.

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Development of Seismic Demand for Chang-Bin Offshore Wind Farm in Taiwan Strait

Cited by 12 publications

References 6 publications

Seismic Fragility Analysis of Monopile Offshore Wind Turbines under Different Operational Conditions

Seismic Fragility Analysis of Monopile Offshore Wind Turbines under Different Operational Conditions

Effect of Scour on the Natural Frequency Responses of the Meteorological Mast in the Taiwan Strait

An Investigation into the Effect of Scour on the Loading and Deformation Responses of Monopile Foundations

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