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Research Papers: Structures and Safety Reliability

Alternative Environmental Contours for Marine Structural Design—A Comparison Study1

[+] Author and Article Information
Erik Vanem

Strategic Research and Innovation,
DNV-GL,
Høvik 1363, Norway
e-mail: Erik.Vanem@dnvgl.com

Elzbieta M. Bitner-Gregersen

Strategic Research and Innovation,
DNV-GL,
Høvik 1363, Norway
e-mail: Elzbieta.Bitner-Gregersen@dnvgl.com

1Paper presented at the 2014 ASME 33rd International Conference on Ocean, Offshore and Arctic Engineering, San Francisco, CA, June 8–13, 2014, Paper No. OMAE2014-23252.

Contributed by the Ocean, Offshore, and Arctic Engineering Division of ASME for publication in the JOURNAL OF OFFSHORE MECHANICS AND ARCTIC ENGINEERING. Manuscript received June 18, 2014; final manuscript received July 3, 2015; published online August 6, 2015. Assoc. Editor: Carlos Guedes Soares.

J. Offshore Mech. Arct. Eng 137(5), 051601 (Aug 06, 2015) (8 pages) Paper No: OMAE-14-1064; doi: 10.1115/1.4031063 History: Received June 18, 2014

A new approach to estimate environmental contours in the original physical space by direct Monte Carlo simulations rather than applying the Rosenblatt transformation has recently been proposed. In this paper, the new and the traditional approach to estimating the contours are presented and the assumptions on which they are based are discussed. The different results given by these two methods are then compared in a number of case studies. Simultaneous probability density functions are fitted to the joint distribution of significant wave height and wave period for selected ocean locations and environmental contours are estimated for both methods. Thus, the practical consequences of the choice of approach are assessed. Particular attention is given to mixed sea systems. In these situations, the two approaches to environmental contours may be very different while for other wave conditions the contours are similar.

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References

Haver, S. , 1987, “On the Joint Distribution of Heights and Periods of Sea Waves,” Ocean Eng., 14(5), pp. 359–376. [CrossRef]
Winterstein, S. , Ude, T. , Cornell, C. , Bjerager, P. , and Haver, S. , 1993, “Environmental Parameters for Extreme Response: Inverse FORM With Omission Factors,” 6th International Conference on Structural Safety and Reliability.
Huseby, A. B. , Vanem, E. , and Natvig, B. , 2013, “A New Approach to Environmental Contours for Ocean Engineering Applications Based on Direct Monte Carlo Simulations,” Ocean Eng., 60, pp. 124–135. [CrossRef]
Huseby, A. B. , Vanem, E. , and Natvig, B. , 2013, “A New Method for Environmental Contours in Marine Structural Design,” ASME Paper No. OMAE2013-10053.
Rosenblatt, M. , 1952, “Remarks on a Multivariate Transformation,” Ann. Math. Stat., 23(3), pp. 470–472. [CrossRef]
Haver, S. , and Winterstein, S. , 2009, “Environmental Contour Lines: A Method for Estimating Long Term Extremes by a Short Term Analysis,” Trans. Soc. Nav. Archit. Mar. Eng., 116, pp. 116–127.
Vanem, E. , and Bitner-Gregersen, E. , 2012, “Stochastic Modelling of Long-Term Trends in the Wave Climate and Its Potential Impact on Ship Structural Loads,” Appl. Ocean Res., 37, pp. 235–248. [CrossRef]
Baarholm, G. S. , Haver, S. , and Økland, O. D. , 2010, “Combining Contours of Significant Wave Height and Peak Period With Platform Response Distributions for Predicting Design Response,” Mar. Struct., 23(2), pp. 147–163. [CrossRef]
Leira, B. J. , 2008, “A Comparison of Stochastic Process Models for Definition of Design Contours,” Struct. Saf., 30(6), pp. 493–505. [CrossRef]
Sagrilo, L. , Næss, A. , and Doria, A. , 2011, “On the Long-Term Response of Marine Structures,” Appl. Ocean Res., 33(3), pp. 208–214. [CrossRef]
Moan, T. , Gao, Z. , and Ayala-Uraga, E. , 2005, “Uncertainty of Wave-Induced Response of Marine Structures Due to Long-Term Variation of Extratropical Wave Conditions,” Mar. Struct., 18(4), pp. 359–382. [CrossRef]
Jonathan, P. , Ewans, K. , and Flynn, J. , 2011, “On the Estimation of Ocean Engineering Design Contours,” ASME Paper No. OMAE2011-49886, pp. 695–705.
Huseby, A. B. , Vanem, E. , and Natvig, B. , 2015, “Alternative Environmental Contours for Structural Reliability Analysis,” Struct. Saf., 54, pp. 32–45. [CrossRef]
Bitner-Gregersen, E. , 2012, “Joint Long Term Models of Met-Ocean Parameters,” Marine Technology and Engineering: CENTEC Anniversary Book, C. Guedes Soares , Y. Garbatov , N. Fonseca , and A. Teixeira , eds., Vol. 1., CRC Press, London, pp. 19–34.
Bitner-Gregersen, E. , and Haver, S. , 1989, “Joint Long Term Description of Environmental Parameters for Structural Response Calculation,” 2nd International Workshop on Wave Hindcasting and Forecasting.
Bitner-Gregersen, E. , and Haver, S. , 1991, “Joint Environmental Model for Reliability Calculations,” First International Offshore and Polar Engineering Conference (ISOPE), The International Society of Offshore and Polar Engineering (ISOPE).
Bitner-Gregersen, E. , 2005, “Joint Probabilistic Description for Combined Seas,” ASME Paper No. OMAE2005-67382, pp. 169–180.
Bitner-Gregersen, E. , 2010, “Uncertainties of Joint Long-Term Probabilistic Modeling of Wind Sea and Swell,” ASME Paper No. OMAE2010-20682, pp. 493–504.
Huseby, A. B. , Vanem, E. , and Natvig, B. , 2014, “A New Monte Carlo Method for Environmental Contour Estimation,” European Safety and Reliability Conference (ESREL), pp. 2091–2098.
Ewans, K. , Bitner-Gregersen, E. , and Guedes Soares, C. , 2006, “Estimation of Wind-Sea and Swell Components in a Bimodal Sea State,” ASME J. Offshore Mech. Arct. Eng., 128(4), pp. 265–270. [CrossRef]

Figures

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Fig. 1

Approximate locations for the fitted wave height and period distributions

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Fig. 2

Environmental contours for one-, ten-, and 25-yr environmental conditions of West Shetland obtained with the traditional method: total sea (top), wind sea (middle), and swell (bottom)

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Fig. 3

Environmental contours for one-, ten-, and 25-yr environmental conditions of West Shetland obtained from 5 × 106 samples: total sea (top), wind sea (middle), and swell (bottom)

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Fig. 4

Environmental contours for one-, ten-, and 25-yr environmental conditions of Western Africa obtained from the traditional method: swell component only

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Fig. 5

Environmental contours for one-, ten-, and 25-yr environmental conditions of Western Africa obtained from 5 × 106 samples: swell component

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Fig. 6

Environmental contours for one-, ten-, and 25-yr environmental conditions of NWS Australia obtained from the traditional method: total sea (top), wind sea (middle), and swell (bottom)

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Fig. 7

Environmental contours for one-, ten-, and 25-yr environmental conditions of NWS Australia obtained from 5 × 106 samples: total sea (top), wind sea (middle), and swell (bottom)

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Fig. 8

Illustration of how even remote samples in the parameter space contribute in estimation of the contour segments with the new approach

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Fig. 9

A possible modification of the new approach in areas with mixed sea, include only samples within a specified sector in the estimation of the contour segments

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