Vortex Induced Vibrations (VIV) as a structurally relevant incident

Tower with damper to protect against vortex induced vibrations ViV

Such vibrations are widely known for its destructive nature if running out of control.

OWT has developed a significant competence in this sector. This includes regular design scenarios as well as analysing occurences of unexpected excitations. Our projects also include collaboration with damper designers to find the most suitable solution.

In one case we have analysed video footage to determine actual vibration parameters and derivated its impact on the fatigue life time. We were able to process large amounts of data logs to determine the characteristics of this excitation. We could further support with fracture mechanics and inspections planning to finally manage the structure successfully.

In a second case we have been technically supervising a major campaign to provide the necessary information for a installation scenario. In this scenario six towers were prefabricated at the quay side ahead of further installation. In addition, three towers were positioned close together on the installation ship.

In earlier projects excitations have been observed which where were considered to have the potential for severe consequences. Therefore, in this project all steps are taken to secure this scenario.

Modeling in a wind tunnel was carried out in order to take into account not only vortex-induced effects, but also channel effects and gallopping. The effectiveness of the chosen countermeasures was also confirmed. It made it possible to design the foundations on the quay and on the ship sufficiently safe with regard to ULS and fatigue.

VIVs are certainly not to be underestimated in their effect, but also in their sensitivity to various basic parameters. OWT can provide support with its knowledge and experience.