Journal of the Computational Structural Engineering Institute of Korea (한국전산구조공학회논문집)

Computational Structural Engineering Institute of Korea (한국전산구조공학회)
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Reliability-Based Design Optimization of 130m Class Fixed-Type Offshore Platform

신뢰성 기반 최적설계를 이용한 130m급 고정식 해양구조물 최적설계 개발

  • 김현석 (한국해양과학기술원 부설 선박해양플랜트연구소 친환경연료추진연구본부) ;
  • 김현성 (한국해양과학기술원 부설 선박해양플랜트연구소 해양플랜트연구본부) ;
  • 박병재 (한국해양과학기술원 부설 선박해양플랜트연구소 해양플랜트연구본부) ;
  • 이강수 (한국해양과학기술원 부설 선박해양플랜트연구소 해양플랜트연구본부)
  • Received : 2021.05.31
  • Accepted : 2021.07.20
  • Published : 2021.10.31
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Abstract

In this study, a reliability-based design optimization of a 130-m class fixed-type offshore platform, to be installed in the North Sea, was carried out, while considering environmental, material, and manufacturing uncertainties to enhance its structural safety and economic aspects. For the reliability analysis, and reliability-based design optimization of the structural integrity, unity check values (defined as the ratio between working and allowable stress, for axial, bending, and shear stresses), of the members of the offshore platform were considered as constraints. Weight of the supporting jacket structure was minimized to reduce the manufacturing cost of the offshore platform. Statistical characteristics of uncertainties were defined based on observed and measured data references. Reliability analysis and reliability-based design optimization of a jacket-type offshore structure were computationally burdensome due to the large number of members; therefore, we suggested a method for variable screening, based on the importance of their output responses, to reduce the dimension of the problem. Furthermore, a deterministic design optimization was carried out prior to the reliability-based design optimization, to improve overall computational efficiency. Finally, the optimal design obtained was compared with the conventional rule-based offshore platform design in terms of safety and cost.

본 연구에서는 환경, 재료 물성 및 제작 등에서의 불확실성을 고려하여 130m급 고정식 해양구조물의 신뢰성 기반 최적설계를 수행하였다. 구조물의 구조건전성을 엄밀하게 반영하기 위해 작용 및 허용 응력의 비인 UC 값을 신뢰성 해석 및 신뢰성 기반 최적설계의 제약조건으로 고려하였다. 해양구조물의 제작비용을 저감하기 위해 자켓형 지지구조물의 중량을 최소화하였다. 불확실성의 통계적 특성은 문헌 등을 참고하여 관측되거나 측정된 데이터를 기반으로 정의하였다. 자켓형 해양구조물의 신뢰성 해석과 신뢰 기반 최적설계는 부재 수가 많아 계산 부담이 큼으로 문제의 차원을 축소하기 위해 응답의 중요성을 기준으로 설계변수를 선별할 수 있는 방법을 제안한다. 또한 효율적인 계산을 위해 신뢰성 기반 최적설계를 수행하기 전 결정론적 최적설계를 먼저 수행하였다. 마지막으로, 도출된 최적설계(안)을 기존 각 급 규정 기반 설계와 안전성 및 경제성 측면에서 비교 분석하였다.

Keywords

Acknowledgement

본 논문은 선박해양플랜트연구소 주요사업 "불확실성을 고려한 유탄성 기반 해양구조물 구조손상도평가 핵심기술 개발(2/5)"로 수행된 연구결과입니다(PES3930).

References

  1. AISC (2014) Steel Construction Manual, 14th Edition, American Institute of Steel Construction.
  2. Alpsten, G. (1972) Variations in Mechanical and Cross-Sectional Properties of Steel, State of the Art Report, Proc. Int. Conf. Planning & Design of Tall Buildings, ASCE-IABSE, Lehigh University.
  3. API RP 2A-WSD (2000) Recommended Practice for Planning, Designin and Constructing Fixed Offhshore Platforms - Working Stress Design 21st Edition, American Petroleum Institute.
  4. Ashkenazy, Y., Gildor, H. (2011) On The Probability and Spatial Distribution of Ocean Surface Currents, J. Phys. Oceanogr., 41(12), pp.2295~2306. https://doi.org/10.1175/JPO-D-11-04.1
  5. Bentley (2019) SACS User Manual, Bentley, USA.
  6. DNV REPORT NO. 95-2018 (1996) Guideline for Offshore Structural Reliability Analysis: General.
  7. DNV REPORT NO. 95-3204 (1996) Guideline for Offshore Structural Reliability Analysis: Examples for Jacket Platforms.
  8. DNVGL-OS-E301 (2018) Offshore Standard - Position Mooring, Det Norske Veritas and Germanischer Lloyd.
  9. Fadaee, M.J., Besharat, M. (2005) Design Optimization of Offshore Platforms using Genetic Algorithms and Wave-Net, Proceedings of the 8th International Conference on the Application of Artificial Intelligence to Civil, Structural and Environmental Engineering, p.38.
  10. Havard, V., Kjell, A.O., Henrik, S., Henning, W. (2018) Analysis of Tidal Currents in the North Sea from Shipboard Acoustic Doppler Current Profiler Data, Continental Shelf Research, 162, pp.1~12. https://doi.org/10.1016/j.csr.2018.04.001
  11. Johannessen, K., Meling, T.S., Hayer, S. (2001) Joint Distribution for Wind and Waves in the Northern North Sea, The 11th International Offshore and Polar Engineering Conference, pp.19~28.
  12. Jung, T.-W., Kim, B.-M., Ha, S.-H. (2017) A Study on Lightweight Design of Cantilever-type Helideck Using Topology Design Optimization, J. Comput. Struct. Eng. Ins. Korea, 30(5), pp.453~460. https://doi.org/10.7734/COSEIK.2017.30.5.453
  13. Kim, H.-S., Kim. H.-S., Park, B., Lee, K. (2020) 3D Topology Optimization of Fixed Offshore Structure and Experimental Validation, J. Ocean Eng. & Technol., 34(4), pp.1~9. https://doi.org/10.26748/KSOE.2019.111
  14. Lee, K., Park, B., Kim, H-S., Kim, D., (2018) Study of Rule Scantling Method and Structural Strength Evaluation to Obtain Structural Design Technology for Fixed Offshore Platform, KRISO Technical Report, 58, pp.69~79.
  15. Lee, Y.-S., Choi, B.-L., Lee, J.H., Kim, S.Y. Han, S. (2014) Reliability-Based Design Optimization of Monopile Transition Piece for Offshore Wind Turbine System, Renew. Energy, 71, pp.729~741. https://doi.org/10.1016/j.renene.2014.06.017
  16. Nasseri, T., Shabakhty, N., Afshar, M.H. (2014) Study of Fixed Jacket Offshore Platform in the Optimization Design Process under Environmental Loads, Int. J. Marit. Technol., 2, pp.75~84.
  17. Park, Y., Park, H.-C. (2014) Optimal Design of Wind Turbine Tower Model Using Reliability-Based Design Optimization, Trans. Korean Soc. Mech. Eng.-A, 38(5), pp.575~584. https://doi.org/10.3795/KSME-A.2014.38.5.575
  18. Peter, C.C. (2008) Probability Distribution Function of the Upper Equatorial Pacific Current Speeds, Geophys. Res. Lett., 35(12), pp.1~18. https://doi.org/10.1029/2008GL034769
  19. RAMDO Software (2021) RAMDO solutions, LLC, Iowa City, IA, https://www.ramdosolutions.com May 29.
  20. van Ledden, M., van den Berg, N.J.F., de Jong, M.S., van Gelder, P.H .A.J.M., den H eijer, C., Vrikling, J.K., Jonkman, S.N., Roos, P.C., Hulscher, S.J.M.H., Lansen, A.J. (2014) An Idealized Meteorological-Hydrodynamic Model For Exploring Storm Surge Statistics In The North Sea, Coastal Engineering Proceedings, pp.1~12.