Effect of climate change on dynamic behavior of monopile supported offshore wind turbine structure

Abstract

Dynamic behavior of monopile supported offshore wind turbine is challenging due to complex long term wind and wave loading. Design of offshore wind turbine (OWT) structure primarily requires estimation of the fundamental frequency which needs to be kept away from excitation frequencies of wind and wave loading to avoid dynamic amplification of response and early fatigue damage. Global warming changes the wind and wave pattern due to pressure changes over the earth. The effect of climate change is having significant effect on wind speed, significant wave height and wave period, which in turn changes the dynamic behavior of OWT system. Fluctuating wind speed and wave height due to the effect of climate change may result in increased response and early fatigue damage. This study focuses on dynamic behavior of the monopile supported offshore wind turbine structure due to the climate change variability corresponding to 50 years future wind speed values. Historic wind data is utilized to project the future wind speed. The system is modeled using a beam on nonlinear Winkler foundation model. Soil resistance is modeled using American Petroleum Institute based cyclic p-y and t-z curves. The dynamic response and change in fatigue life of OWT structure is examined due to the effect of climate change and design implications are also suggested.