Design of Foundations for Offshore Wind Turbines

Appendix CTower Idealisation

The towers of offshore wind turbines are tapered towers with diameters decreasing from the bottom to the top. Typically, the wall thickness of the tower also decreases with height. However, some small and medium‐sized turbines have constant wall thickness. The formulation presented in this book (Chapter 5 – Sections 5.4.1 and 5.8) replaces this tower shape with an equivalent constant diameter, constant wall thickness tower. The average tower diameter

C.1

is used in combination with an equivalent tower wall thickness t_T. Note that if the average wall thickness is determined from a range of wall thicknesses of the tower or from the mean of the top and bottom wall thicknesses, then the tower mass, as calculated from the idealised tower geometry,

C.2

may not be the same as the actual tower mass m_T. In the case that information about tower wall thickness is not available, the equivalent thickness can be chosen such that the actual tower mass is maintained, that is,

C.3

The nondimensional stiffness parameters are normalised with the length L_T and the bending stiffness E_TI_T of the tower. When calculating these nondimensional stiffness parameters, the equivalent ...