Assessment of Hurricane Loads for Ultimate Limit State Analysis of Offshore Wind Turbine Monopiles
Gideon, Roan.
2021
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Thesis (M.S.)--Tufts
University, 2021.
Submitted to the Dept. of Civil Engineering.
Advisor: Eric Hines.
Committee: Dan Kuchma, and Garrett Barter.
Keywords: Energy, Civil engineering, and Ocean engineering.
Ultimate limit state (ULS) loads for offshore wind monopile support structures are investigated at two wind energy areas on the U.S. East ... read moreCoast, with particular focus on the characterization of hurricane loads. Metocean conditions prescribed by multiple design standards for offshore wind support structures in hurricane regions are characterized using both hindcast data and a synthetic hurricane catalogue resulting in different outcomes for the design loads. Using the estimated return interval hurricane metocean conditions, the mudline moment is computed for the IEA 15MW reference wind turbine using both approximate calculations and computational OpenFAST simulations for comparison. Approximate calculations produce estimates of mudline moments under operating conditions with steady wind speeds that correspond well to computational results. Similarly, approximate calculations for extreme conditions with turbulent wind speeds and irregular waves yield results that are comparable to computational analysis. However, significant differences between approximate calculations and computational results are observed for operating conditions with turbulent wind speeds and for extreme conditions that consider only wind loads or only wave loads. It is found that the reasonable agreement between approximate and computational results for extreme conditions with both turbulent wind speeds and irregular waves may be due to a combination of overestimation of mudline moment due to wind and underestimation of mudline moment due to waves by the approximate calculation. The methodology used, either approximate calculation or OpenFAST simulation, can significantly affect the conclusions drawn regarding whether operating or extreme load cases dominate the ULS design of offshore wind monopiles at a particular site.read less - ID:
- rb68xs56f
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