A spectral model for forces due to ice crushing

Tuomo Kärnä, Yan Qu, Xiangjun Bi, Qianjin Yue, Walter Kuehnlein

Research output: Contribution to journalArticleScientificpeer-review

29 Citations (Scopus)

Abstract

This paper presents a model of dynamic ice forces on vertical offshore structures. The model concerns a loading scenario where a competent ice sheet is drifting and crushing against the structure. Full scale data obtained on two offshore structures were used in the derivation of a method that applies both to narrow and wide structures. A large amount of events with directly measured local forces was used to derive formulas for spectral density functions of the local ice forces. A nondimensional formula that was derived for the autospectral density is independent of ice thickness. Coherence functions were used to define cross-spectral density functions of the local ice forces. The two kind of spectral density functions were used to obtain the spectral density of the total ice force. The method takes into account both the spatial and time correlation between the local forces. Accordingly, the model provides a tool to consider the nonsimultaneous characteristics of the local ice pressures while assessing the total ice force.
Original languageEnglish
Pages (from-to)138-145
JournalJournal of Offshore Mechanics and Arctic Engineering
Volume129
Issue number2
DOIs
Publication statusPublished - 2007
MoE publication typeA1 Journal article-refereed

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Crushing
Ice
Spectral density
Probability density function
Offshore structures

Keywords

  • ice forces
  • ice crushing
  • vibrations
  • spectral model

Cite this

Kärnä, Tuomo ; Qu, Yan ; Bi, Xiangjun ; Yue, Qianjin ; Kuehnlein, Walter. / A spectral model for forces due to ice crushing. In: Journal of Offshore Mechanics and Arctic Engineering. 2007 ; Vol. 129, No. 2. pp. 138-145.
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Kärnä, T, Qu, Y, Bi, X, Yue, Q & Kuehnlein, W 2007, 'A spectral model for forces due to ice crushing', Journal of Offshore Mechanics and Arctic Engineering, vol. 129, no. 2, pp. 138-145. https://doi.org/10.1115/1.2426997

A spectral model for forces due to ice crushing. / Kärnä, Tuomo; Qu, Yan; Bi, Xiangjun; Yue, Qianjin; Kuehnlein, Walter.

In: Journal of Offshore Mechanics and Arctic Engineering, Vol. 129, No. 2, 2007, p. 138-145.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - A spectral model for forces due to ice crushing

AU - Kärnä, Tuomo

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AU - Bi, Xiangjun

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AB - This paper presents a model of dynamic ice forces on vertical offshore structures. The model concerns a loading scenario where a competent ice sheet is drifting and crushing against the structure. Full scale data obtained on two offshore structures were used in the derivation of a method that applies both to narrow and wide structures. A large amount of events with directly measured local forces was used to derive formulas for spectral density functions of the local ice forces. A nondimensional formula that was derived for the autospectral density is independent of ice thickness. Coherence functions were used to define cross-spectral density functions of the local ice forces. The two kind of spectral density functions were used to obtain the spectral density of the total ice force. The method takes into account both the spatial and time correlation between the local forces. Accordingly, the model provides a tool to consider the nonsimultaneous characteristics of the local ice pressures while assessing the total ice force.

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KW - vibrations

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