Probability Analysis of Wave Run-Ups and Air Gap Response of a Deepwater Semisubmersible Platform Using LH-Moments Estimation Method
Publication: Journal of Waterway, Port, Coastal, and Ocean Engineering
Volume 142, Issue 2
Abstract
The air gap response in harsh environments, a critical design issue for offshore platforms, is related to the wave run-ups attributable to wave-platform interactions and has the potential to result in serious wave impacts. Therefore, the reliable prediction of wave run-ups and air gap response in harsh environments is a challenging task and needs further study. In this study, probability analysis of the wave run-up data from an experimental study of a deepwater semisubmersible platform was conducted based on the three-parameter Weibull distribution model using the LH-moments method for parameter estimation. One of the highlights in the present study is that the explicit relationships between the first three LH-moments at arbitrary levels and the parameters of the Weibull distribution were established analytically. The accuracy of LH-kurtosis estimation was proposed to determine the appropriate level for probability analysis. The air gap response was found to be more serious in quartering and beam seas than in head seas. In front of the columns along the incoming-wave direction, especially the aft one, the wave run-ups showed higher probability distributions than did the other platform areas, leading to higher likeliness of suffering from negative air gap and wave impact accidents. At the platform center, the wave run-up was found to be significantly lower than the incident wave. This research shows that the probability distributions based on LH-moments at the appropriate level can well represent large wave run-ups, except for that beyond the still-water air gap, where both measurement methods and probability analyses warrant further research.
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Acknowledgments
The authors acknowledge the support of the National Natural Science Foundation of China (Grant Nos. 51279104 and 51239007) and the project of the CNOOC-SJTU Deepwater Engineering Research Center. The authors are grateful to the anonymous reviewers whose valuable comments and suggestions improved the manuscript.
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Published In
Journal of Waterway, Port, Coastal, and Ocean Engineering
Volume 142 • Issue 2 • March 2016
Copyright
© 2015 American Society of Civil Engineers.
History
Received: Dec 11, 2014
Accepted: Aug 12, 2015
Published online: Dec 14, 2015
Published in print: Mar 1, 2016
Discussion open until: May 14, 2016
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