Coupled hydrodynamic and geotechnical analysis of jacket offshore wind turbine

K.A. Abhinav, Nilanjan Saha

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

This paper compares the response of a jacket-supported offshore wind turbine (OWT) under wave loading, when (a) soil–structure interaction (SSI) is ignored and (b) SSI is considered. The jacket is placed in a water depth of 70 m and soil conditions off the west coast of India are used in the study. The rotor of the OWT is considered to be parked, under a survival average wind speed of 50 m/s, significant waver height Hs¼16 m and peak spectral period Tp¼18 s. The significance of includng SSI in OWT studies is investigated by means of pushover analyses and irregular-wave dynamic analyses. Modal studies are performed to determine the variation in the free-vibration response of the two cases. It is observed that ignoring SSI tends to over-estimate the ultimate strength characteristics of the OWT by 3–60% in various modes or increase the tower top displacement above serviceable limit. For dynamics analysis, the wave elevation is generated using wave superposition method. The JONSWAP wave spectrum is discretized using constant area method which introduces additional uncertainty. The analysis shows that approximately 200 frequencies are necessary using constant area method to capture the tail region appropriately. Also the statistical uncertainty in the generation of wave elevation for dynamic analyses is quantified by means of sample convergence studies. The results show that approximately 20–40 samples are required in order to obtain reasonable statistics.
Original languageEnglish
Pages (from-to)66-79
Number of pages14
JournalSoil Dynamics and Earthquake Engineering
Volume73
Early online date24 Mar 2015
DOIs
Publication statusPublished - 30 Jun 2015

Keywords

  • jacket offshore wind turbine
  • soil–structure interaction
  • nonlinear dynamic analysis
  • hydrodynamic uncertainty
  • random wave loading

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