Posters
Come meet the poster presenters to ask them questions and discuss their work
We would like to invite you to come and see the posters at our upcoming conference. The posters will showcase a diverse range of research topics, and will give delegates an opportunity to engage with the authors and learn more about their work. Whether you are a seasoned researcher or simply curious about the latest developments in your field, we believe that the posters will offer something of interest to everyone. So please join us at the conference and take advantage of this opportunity to learn and engage with your peers in industry and the academic community.
PO220: Analysis and validation of modelling approaches for Splashzone-lowering of structures with large hydrodynamic footprints
Dion Pluijlaar, Senior Marine Engineer, Heerema Marine Contractors
Abstract
The modelling of Offshore Splashzone-lowering is notoriously complex and remains one of the most difficult to analyze stages of the installation operations of (partly) submerged structures. This is exacerbated for structures with large hydrodynamic footprints like mudmats, GBSs (Gravity Based Structures) and SBJs (Suction Bucket Jackets). The large surface areas are susceptible to slamming forces while the (hydro)dynamic properties change virtually instantly when the structure passes the waterline. Phenomena like added mass result in a sudden change of CoG (Centre of Gravity) position and dynamic mass, which can instantly change the dynamic behavior of the system. For example the natural period of the second pendulum mode for a SBJ increases such that the natural period of this mode moves into the range of typical wind-sea wave spectra encountered on locations suitable for windfarm development, posing challenges for installation. Analyses have been performed in project preparation phase to accurately predict dynamic behavior, supported by model testing and CFD studies to provide input for modelling in frequency and time domain; key output (e.g. DAF (Dynamic Amplification Factor) and side- and off-lead angles for the hoist wire, rigging, lifting tools and crane) is obtained. The model predicted output is compared to offshore observations and measuring campaigns during installation of repetitive foundation installation projects. This comparison provides valuable insights on modelling choices for the Splashzone lowering stage. It is shown how choices and assumptions can easily lead to an overly conservative representation of this highly non-linear stage. On the other hand, if key dynamics are not properly captured and identified, the model may fail to reflect the true behavior of the system and paint a too optimistic picture.
