The effect of marine growth and damage severity on the modal parameters of offshore wind turbine supporting structures: an experimental study

This contribution investigates the effect of marine growth and damage severity on the modal parameters of a scaled experimental model of a monopile used in supporting offshore wind turbines. A quick glimpse of the literature review reveals that this topic has not been well investigated as the majority of previous research focuses on the effect of marine growth on the hydrodynamic loads transferred to the test structure, with little focus on its effect on the modal parameters of a structure. Nevertheless, from a monitoring standpoint, it is important to differentiate between the effect of marine growth and damage on the modal parameters, especially when these parameters are used as damage indicators, further improving existing structural health monitoring techniques in determining if the changes observed in modal parameters are caused by actual damage rather than the growth of marine organisms with time. The results provided in this contribution provide differences between the effect of marine growth and damage, which is recommended to be included in current monitoring techniques. Furthermore, a recommendation to investigate the effect of damage on damping and, possibly, the potential of using changes in damping characteristics as damage indicators is also made.