Contents

An extreme loading study has been conducted comprising a general wind climate analysis as well as a wind turbine reliability study. In the wind climate analysis, the distribution of the (horizontal) turbulence standard deviation, conditioned on the mean wind speed, has been approximated by fitting a three parameter Weibull distribution to the measured on-shore and off-shore data for wind speed variations. Specific recommendations on off-shore design turbulence intensities are lacking in the present IEC-code. Based on the present analysis of the off-shore wind climate on two shallow water sites, a design turbulence intensity for off-shore application is proposed which, in the IEC code framework, is applicable for extreme as well as for fatigue load determination. In order to establish a rational method to analyse wind turbine components with respect to failure in ultimate loading, and in addition to establish partial safety factors for design of such components against this failure mode, structural reliability methods must be applied. This type of analysis accounts for the variability of the external (wind) loading (a