Load analysis on an offshore wind turbine structure

Abstract

This report is written as documentation of a master thesis in the course constructions and materials at the University of Stavanger. The thesis was performed within January to June 2012 as a further research on an international simulation code comparison project. The problem description in this thesis is as follows: • How does an offshore jacket structure respond to different mean wind speeds and different turbulence intensities? The offshore wind turbine jacket structure was measured to see how changing winds and turbulence intensities affects the loads on the structures. In all simulated cases the wind turbine was in operating condition. Loads at given positions in the simulation were further analyzed to create damage equivalent load cycles. Simulation results were collected from a multi-body simulation program where the pre modeled wind turbine and jacket structure was tested. The result of the simulations shows loads in given positions of the structure, as well as Eigen frequencies and damage equivalent loads. Conclusions states: • The damage equivalent loads rise nearly linearly with rising wind speeds • By increasing the turbulence intensity the damage equivalent loads rise at a higher rate • With a wind speed of 9 meters per second and turbulence intensity of 20,2% (2 standard deviations) the wind turbine reacts with resonance behavior.