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China Ocean Engineering

, Volume 30, Issue 4, pp 535–548 | Cite as

Sensitivity analysis of air gap motion with respect to wind load and mooring system for semi-submersible platform design

  • Fa-li Huo (霍发力)
  • Yan Nie (聂 焱)
  • De-qing Yang (杨德庆)Email author
  • Gang Dong (董 刚)
  • Jin Cui (崔 锦)
Article

Abstract

A design of semi-submersible platform is mainly based on the extreme response analysis due to the forces experienced by the components during lifetime. The external loads can induce the extreme air gap response and potential deck impact to the semi-submersible platform. It is important to predict air gap response of platforms accurately in order to check the strength of local structures which withstand the wave slamming due to negative air gap. The wind load cannot be simulated easily by model test in towing tank whereas it can be simulated accurately in wind tunnel test. Furthermore, full scale simulation of the mooring system in model test is still a tuff work especially the stiffness of the mooring system. Owing to the above mentioned problem, the model test results are not accurate enough for air gap evaluation. The aim of this paper is to present sensitivity analysis results of air gap motion with respect to the mooring system and wind load for the design of semi-submersible platform. Though the model test results are not suitable for the direct evaluation of air gap, they can be used as a good basis for tuning the radiation damping and viscous drag in numerical simulation. In the presented design example, a numerical model is tuned and validated by ANSYS AQWA based on the model test results with a simple 4 line symmetrical horizontal soft mooring system. According to the tuned numerical model, sensitivity analysis studies of air gap motion with respect to the mooring system and wind load are performed in time domain. Three mooring systems and five simulation cases about the presented platform are simulated based on the results of wind tunnel tests and sea-keeping tests. The sensitivity analysis results are valuable for the floating platform design.

Key words

mooring system air gap semi-submersible platform radiation damping viscous drag 

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References

  1. Bitner-Gregersen, E. M., 2005. Joint probabilistic description for combined seas, Proceedings of the 24th International Conference on Offshore Mechanics and Arctic Engineering, Halkidiki, Greece.Google Scholar
  2. DNV (Det Norske Veritas), 2010. DNV-RP-C205: Environmental Conditions and Environmental Loads, October, 2010.Google Scholar
  3. DNV (Det Norske Veritas), 2012a. DNV-OS-C103: Structural Design of Column Stabilised Units (LRFD Method), October, 2012.Google Scholar
  4. DNV (Det Norske Veritas), 2012b. DNV-RP-C103: Column-Stabilised Units, April, 2012.Google Scholar
  5. Kazemi, S. and Incecik, A., 2007. Theoretical and experiment analysis of air gap response and wave-on-deck impact of floating offshore structures, Proceedings of the 26th International Conference on Offshore Mechanics and Arctic Engineering, San Diego, California, USA, OMAE2007-29288, 297–304.Google Scholar
  6. Kazemi, S. and Incecik, A., 2005. Numerical prediction of air gap response of floating offshore structures using direct boundary element method, Proceedings of the 24th International Conference on Offshore Mechanics and Arctic Engineering, Halkidiki, Greece, 7399, 803–809.Google Scholar
  7. Liang, X. F., Yang, J. M., Xiao, L. F., Li, X. and Li, J., 2010. Numerical study of air gap response and wave impact load on a moored semi-submersible platform in predetermined irregular wave train, Proceedings of the 29th International Conference on Ocean, Offshore and Arctic Engineering, Shanghai, China, OMAE 2010–20230.Google Scholar
  8. Lwanowski, B. and Wemmenhove, R., 2009. CFD simulation of wave run-up on a semi-submersible and comparisonwith experiment, Proceedings of the 28th International Conference on Offshore Mechanics and Arctic Engineering, Honolulu, Hawaii, USA, 9052, 19–29.Google Scholar
  9. Matsumto, F. T., Watai, R. A. and Simos, A. N., 2010. Wave run-up and air gap prediction for a largevolumesemi-submersible platform, Proceedings of the 29th International Conference on Offshore Mechanics and Arctic Engineering, Shanghai, China, OMAE2010-20165, 151–159.Google Scholar
  10. Priyanton, A., Maimun, A., Kader, A. S. A., Nasrudin, I., Ghani, M. P. A., Nur, I. and Jaswar, K., 2014. Probability distribution of wave run up and dynamic response on a large volume semi-submersible, Ocean Eng., 76, 52–64.CrossRefGoogle Scholar
  11. Rudman, M. and Cleary, P. W., 2013. Rogue wave impact on a tension leg platform: The effect of wave incidence angle and mooring line tension, Ocean Eng., 61, 123–138.CrossRefGoogle Scholar
  12. Shan, T. B., Yang, J. M., Li, X. and Xiao, L. F., 2011. Experimental investigation on wave run-up characteristics along columns and air gap response of semi-submersible platform, Journal of Hydrodynamics, 23(5): 625–636.CrossRefGoogle Scholar
  13. Simos, A. N., Sparano, J. V. and Aranha, J. A. P. and Matos, V. L. F., 2008. 2nd order hydrodynamic effects on resonant heave, pitch and roll motions of a large-volume semi-submersible platform, Proceeding of the 27th International Conference on Offshore Mechanics and Artic Engineering, Estoril, Portugal, OMAE2008-57430, 229–237.Google Scholar
  14. Sweetman, B. and Winterstein, S. R., 2001. Air gap prediction: Use of second-order diffraction and multi-column models, Proceedings of the 14th International Offshore and Polar Engineering Conference, Stavanger, Norway, 390–397.Google Scholar
  15. Winterstein, S., Ude, T. C., Cornell, C. A., Bjerager, P. and Haver, S., 1993. Environmental parameters for extreme response inverse FORM with omission sensitivity, Proceedings of International Conference on Structural Safety and Reliability, Innsbruck, COSSAR-93.Google Scholar

Copyright information

© Chinese Ocean Engineering Society and Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  • Fa-li Huo (霍发力)
    • 1
    • 2
  • Yan Nie (聂 焱)
    • 3
  • De-qing Yang (杨德庆)
    • 2
    Email author
  • Gang Dong (董 刚)
    • 3
  • Jin Cui (崔 锦)
    • 3
  1. 1.Jiangsu University of Science and TechnologyZhenjiangChina
  2. 2.School of Naval Architecture, Ocean and Civil EngineeringShanghai Jiao Tong UniversityShanghaiChina
  3. 3.Grenland Group (China) Ltd.ShanghaiChina

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