Global motion reconstruction of a steel catenary riser under vessel motion

ABSTRACT

Under vessel motion, dynamic responses of compliant risers, like a steel catenary riser, are no longer small displacement and small deformation problems but characterised with large displacement and small deformation instead. It is therefore difficult to directly obtain the riser global motion based on experimental or field-measured local strain or acceleration data. This paper proposes a generalised global motion reconstruction method for large displacement but small deformation problems, assuming that the global motion can be divided into quasi-static motion and dynamic vibration. The proposed methodology is validated numerically and experimentally with satisfactory accuracy. Parameters like sensor location and mode number to be used in the motion reconstruction are optimised and recommended. Uncertainty analysis considering different noise levels is performed to evaluate the robustness of the proposed method. Most importantly, further comparative hydrodynamic analyses indicate the significance of the drag amplification effect, most probably due to vortex-induced vibrations.

KEYWORDS:

• Motion reconstruction
• riser global motion
• vessel motion
• uncertainty analysis
• hydrodynamic coefficient identification

Acknowledgements

The authors would particularly like to thank Statoil for the permission to use these data for this publication.

Disclosure statement

No potential conflict of interest was reported by the author(s).

ORCID

Jungao Wang http://orcid.org/0000-0003-3024-2951

Additional information

Funding

The authors gratefully acknowledge the financial support from Statoil, Norway, for the research program: VIV effects in sag-bends of SCRs. Support from the National Science Foundation of China [grant number 51279101], [grant number 51490674] and China Scholarship Council are also greatly appreciated.