Probabilistic analysis of operational ice damage for Polar class vessels using full-scale data
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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Date
2024-03
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Mcode
Degree programme
Language
en
Pages
20
Series
STRUCTURAL SAFETY, Volume 107
Abstract
To ensure the safety of maritime operations in polar waters, the IMO enforced the International Code for Ships Operating in Polar Waters (Polar Code) in 2017. To address ice navigation related risks, the Polar Code refers to a set of guidelines known as the Polar Operational Limit Assessment Risk Indexing System (POLARIS). Following POLARIS, operational limits for ice navigation are defined based on the Risk Index Outcome (RIO) value, which takes into account the prevailing ice conditions and the ice class of a ship. Recent studies indicate that the POLARIS guidelines are well-founded. However, no direct relationship between RIO values and the probability of an ice-induced hull structural damage has been established. To enable a more accurate analysis of ice navigation risks, this article addresses this issue by (i) relating measured ice-induced loads to RIO values corresponding to the ice conditions in which the loads were measured, (ii) calculating the load limits for plastic deformation and rupture of the ice belt of hull structures representing different ice classes, and (iii) defining the probability of structural damage for different load limits. The study utilizes long-term full-scale ice load measurements carried out onboard Polar Supply and Research Vessel (PSRV) S.A. Agulhas II in the Antarctic Ocean. The load limits were calculated for ice class standards, PC3, PC4, PC5, PC6, and PC7 in accordance with the Unified Requirements of the International Association of Classification Societies (IACS). On a general level, the results are consistent with earlier findings indicating that the POLARIS guidelines are well-founded. If a ship operates mainly at ‘normal operation’ level, the probability for fracture at hull are at probability levels of 10-3 and 10-4 for ice classes PC3 to PC5. The probability levels for PC6 and PC7 are higher that is possibly a result from conservative load probability distributions. When the portion of operations at ‘special consideration’ level becomes significant, the probability of fracture at the hull increases significantly. However, large ice thicknesses and the largest load magnitudes may be associated with positive RIO values. Some inconsistencies are recognized, and the uncertainty and limitations of the analysis are discussed.Description
Funding Information: This project has received funding from the Lloyd's Register Foundation, a charitable foundation, helping to protect life and property by supporting engineering-related education, public engagement and the application of research www.lrfoundation.org.uk. The data has been collected with funding from the Finnish Funding Agency for Technology and Innovation (Tekes, grant 40508/11) and the Academy of Finland (grant 264354). Furthermore, the authors would like to acknowledge the Department of Environmental Affairs (South Africa) for providing access to the vessel. Special thanks to the crew of S.A. Agulhas II and researchers from Stellenbosch University for assisting in the measurements and practicalities related to those. Mihkel Kõrgesaar acknowledges the financial support by the Estonian Research Council grant PSG754. Funding Information: This project has received funding from the Lloyd's Register Foundation, a charitable foundation, helping to protect life and property by supporting engineering-related education, public engagement and the application of research www.lrfoundation.org.uk. The data has been collected with funding from the Finnish Funding Agency for Technology and Innovation (Tekes, grant 40508/11) and the Academy of Finland (grant 264354). Furthermore, the authors would like to acknowledge the Department of Environmental Affairs (South Africa) for providing access to the vessel. Special thanks to the crew of S.A. Agulhas II and researchers from Stellenbosch University for assisting in the measurements and practicalities related to those. Mihkel Kõrgesaar acknowledges the financial support by the Estonian Research Council grant PSG754. Publisher Copyright: © 2023 The Author(s)
Keywords
Full-scale measurements, Ice load, Load limit states, Polar Code, POLARIS, Structural damage
Other note
Citation
Suominen, M, Kõrgesaar, M, Taylor, R & Bergström, M 2024, ' Probabilistic analysis of operational ice damage for Polar class vessels using full-scale data ', STRUCTURAL SAFETY, vol. 107, 102423 . https://doi.org/10.1016/j.strusafe.2023.102423