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.
Issue Section:
Technical Papers
1.
Peyton
, H. R.
, 1996, “Sea Ice Strength
,” University of Alaska
, Geophysical Institute, Alaska, Rep. No. UAG R-182.2.
Yue
, Q.
, Bi
, X.
, Sun
, B.
, Zhang
, T.
, and Chen
, X.
, 1996, “Full Scale Force Measurement on JZ20-2 Platform
,” Proceedings IAHR Ice Symposium (IAHR’ 96)
, Beijing, August 27–30, pp. 282
–289
.3.
Yue
, Q.
, and Bi
, X.
, 2000, “Ice-Induced Jacket Structure Vibrations in Bohai Sea
,” J. Cold Reg. Eng.
0887-381X, 14
(2
), pp. 81
–92
.4.
Reddy
, D. V.
, Swamidas
, A. S.
, and Cheema
, P. S.
, 1975, “Ice Force Response Spectrum Modal Analysis of Offshore Towers
,” Proceedings 3rd International Conference Port Ocean Eng. Arct. Cond.
, University of Alaska
, 11–15 August, pp. 887
–910
.5.
Reddy
, D. V.
, Cheema
, P. S.
, and Sundarajan
, C.
, 1977, “Relationship Between Response Spectrum and Power Spectral Density Analysis of Ice-Structure Analysis
,” Proceedings 4th International Conference Port Ocean Engineering Arct. Cond.
, Memorial University of Newfoundland
, Canada, 26–30 September, Vol. II
, pp. 664
–683
.6.
Sundararajan
, C.
, and Reddy
, D. V.
, 1973, “Stochastic Analysis of Ice-Structure Interaction
,” Proceeding 2nd Interntational Conference Port Ocean Eng. Arctic Cond. (POAC’73)
, Reykjavik, Iceland, August 27–30, pp. 345
–353
.7.
Määttänen
, M.
, Reddy
, D.
, Arockiasamy
, M.
, and Cheema
, P.
, 1977, “Ice-Structure Interaction Studied on a Lighthouse in the Gulf of Bothnia Using Response Spectrum and Power Spectral Density Function Analyses
,” Proceedings 4th International Conference Port Ocean Engineering Arct. Cond.
, St. John’s, Newfoundland, Canada, September 26–30, pp. 321
–334
.8.
Reddy
, D. V.
, Arockiasamy
, M.
, and Cheema
, P. S.
, 1979, “Non-Stationary Response of Offshore Towers to Ice Loads
,” Proceedings 6th International Conference Port Ocean Engineering Arct. Cond.
, Norwegian Institute of Technology
, Trondheim, Norway, August 13–18, Vol. II
, pp. 1155
–1171
.9.
Kajaste-Rudnitski
, J.
, 1995, On Dynamics of Ice-Structure Interaction
, VTT Publications 276, Technical Research Centre of Finland
, Espoo, Finland.10.
Duan
, M.
, and Liu
, C.
, 1995, “Random Dynamic Analysis of Offshore Structures Under Ice Conditions
,” Proceedings International Conference Struct. Dyn.
, Vibration, Noise and Control. (SDVNC’95), Hong Kong, December 5–7, Vol. 1
, pp. 679
–684
.11.
Ou
, J.
, and Duan
, Z.
, 1996, “The Stochastic Process Model of Ice Acting on Upright Column of Marine Platform and Determination of Model Parameters
,” Proceedings IAHR Ice Symposium
, Beijing, August 27–30, pp. 302
–311
.12.
Määttänen
, M.
, 1978, “On Conditions for the Rise of Self-excited Ice-Induced Autonomous Oscillations in Slender Marine Pile Structures
,” Winter Navigation Board
, Helsinki, Research Rep. No. 25.13.
Eranti
, E.
, 1992, Dynamic Ice Structure Interaction—Theory and Applications
, VTT Publication 90, Technical Research Centre of Finland
, Espoo, Finland.14.
Kärnä
, T.
, and Turunen
, R.
, 1989, “Dynamic Response of Narrow Structures to Ice Crushing
,” Cold Regions Sci. Technol.
0165-232X, 17
, pp. 173
–187
.15.
Kärnä
, T.
, 1992, “A Procedure for Dynamic Soil-Structure-Ice Interaction
,” Proceedings 2nd International Offshore Polar Engineering Conference
, San Francisco, June 14–19, Vol. 2, pp. 769
–771
.16.
Kärnä
, T.
, Kamesaki
, K.
, and Tsukuda
, H.
, 1999, “A Numerical Model for Dynamic Ice-Structure Interaction
,” Comput. Struct.
0045-7949, 72
, pp. 645
–658
.17.
Shkhinek
, K.
, Kärnä
, T.
, Kapustiansky
, S.
, and Jilenkov
, A.
, 2000, “Numerical Simulation of Ice Interaction With a Vertical Wall
,” Proceedings 15th IAHR Ice Symposium
, Gdansk, August 28–September 1, Vol. I
, pp. 231
–242
.18.
Kolari
, K.
, Kouhia
, R.
, and Kärnä
, T.
, 2004, “Ice Failure Analysis Using Strain-Softening Viscoplastic Material Model
.” P.
Neittaanmäki
, T.
Rossi
, and O.
Pironneau
, eds., Porceedings European Congress Compt. Meth. Appl. Sci. Eng.
, Jyväskylä, Finland, 24
–28
July, Vol. 1
, ISBN 951–39-1866-1.19.
Kärnä
, T.
, and Jochmann
, P.
, 2003, “Field Observations on Ice Failure Modes
,” Proceedings 17th International Conference Port Ocean Engineering Arct. Cond.
, Trondheim, Norway, June 16–19, Vol. 2
, pp. 839
–848
.20.
Schwarz
, J.
, and Jochmann
, P.
, 2001, “Ice Force Measurements Within the LOLEIF Project
,” Proceedings 16th Interenational Conference on Port Ocean Engineering Arct. Cond.
, Ottawa, Canada, August 12–17, Vol. 2
, pp. 669
–680
.21.
Jochmann
, P.
, and Schwarz
, J.
, 2001, “Ice Force Measurements at Lighthouse Norströmsgrund—Winter 2000
,” Hamburgische Schiffbau-Versuchsanstalt, Hamburg, LOLEIF Rep. No. 9. Contract No MAS3-CT-97-0098.22.
Bendat
, J. S.
, and Piersol
, A. G.
, 2000, Random Data Analysis and Measurement Procedures
, Wiley
, New York.23.
Stearns
, S. D.
, 2003, Digital Signal Processing With Examples in MATLAB
, CRC
, London.24.
Lin
, Y. K.
, 1967, Probabilistic Theory of Structural Dynamics
, McGraw–Hill
, New York.25.
Newland
, D. E.
, 1975, Random Vibrations and Spectral Analysis
, Longman
, London.26.
Kärnä
, T.
, and Qu
, Y.
, (2005). “Analysis of the Size Effect in Ice Crushing—Edition 1
,” VTT Technical Research Centre of Finland
, Internal Rep. No. RTE-IR-6/2005, Version 2.0, www.karna.euwww.karna.eu27.
Kärnä
, T.
, Qu
, Y.
, and Yue
, Q.
, 2006, “A Model of the Global Ice Force on Vertical Structures
,” Proceedings 18th International Symposium on Ice
, Sapporo, Japan, August 28–September 1, Vol. 3 (in press).28.
Kärnä
, T.
, and Qu
, Y.
, 2006, “An Extreme Value Analysis of Local Pressures
,” Proceedings International Conference Exhibit Performance Ships Structures in Ice
, ICETECH-06, Banff, Canada, July 16–19.29.
Kärnä
, T.
, and Qu
, Y.
, 2006, “An Equivalent Lateral Force for Continuous Crushing
,” Proceedings 25th International Conference Offshore Mech. Arct. Engineering
, Hamburg, Germany, June 4–9.30.
Sodhi
, D.
, Takeuchi
, T.
, Nakazawa
, N.
, Akagawa
, S.
, and Saeki
, H.
, 1988, Cold Regions Sci. Technol.
0165-232X, 28
, pp. 161
–182
.31.
Sodhi
, D.
, 2001, “Crushing Failure During Ice-Structure Interaction
,” Eng. Fract. Mech.
0013-7944, 68
, pp. 1889
–1921
.32.
Sodhi
, D.
, and Haehnel
, B.
, 2003, “Crushing Ice Forces on Structures
,” J. Cold Reg. Eng.
0887-381X, 17
, pp. 153
–170
.33.
Takeuchi
, T.
, Akagawa
, S.
, Saeki
, H.
, Nakazawa
, N.
, and Hirayama
, K.
, 2002, “Ice Load Equation for Level Ice Sheet
,” Int. J. Offshore Polar Eng.
1053-5381, 12
, pp. 171
–177
.34.
Kamesaki
, K.
, Yamauchi
, Y.
, and Kärnä
, T.
, 1996, “Ice Force as a Function of Structural Compliance
,” Proceedings 13th IAHR Ice Symposium
, Beijing, August 27–30, Vol. I
, pp. 395
–402
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