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Probability analysis of wave run-ups and air gap response of a deepwater semi-submersible platform using LH-moments estimation method

Lookup NU author(s): Dr Longfei Xiao, Professor Longbin Tao



This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).


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.

Publication metadata

Author(s): Xiao L, Lu H, Li X, Tao L

Publication type: Article

Publication status: Published

Journal: Journal of Waterway, Port, Coastal and Ocean Engineering

Year: 2016

Volume: 142

Issue: 2

Print publication date: 01/03/2016

Online publication date: 14/12/2015

Acceptance date: 12/08/2015

Date deposited: 25/02/2016

ISSN (print): 0733-950X

ISSN (electronic): 1943-5460

Publisher: ASCE


DOI: 10.1061/(ASCE)WW.1943-5460.0000325


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Funder referenceFunder name
CNOOC-SJTU Deepwater Engineering Research Center
51239007National Natural Science Foundation of China
51279104National Natural Science Foundation of China