Design of Monopile Foundations for Offshore Wind Energy Converters

Abstract

Offshore wind energy converters in water depth up to 20–25 m are mostly built on monopile foundations. Although it is a simple structure the monopile behaviour under transient loading from wind, waves and currents is very complex. Consequently, monopiles are often designed for the relevant extreme load event in a quasi-static approach. However, the effect of cyclic loading on the monopile behaviour has to be analysed as well, but no general accepted procedure currently exists. In the present paper the general design strategy is introduced and a method is suggested to analyse the monopile behaviour under cyclic loading. This method includes a combination of laboratory element tests and an appropriate design method.