Uncertainty quantification in the ice-induced local damage assessment of a hull section

Abstract

For the northernmost ocean regions, where the ice is occasionally present, one must design a robust structure that can withstand rare ice events (i.e., a glacial ice impact). Despite existing engineering practice is well developed, many challenges remain. One of them is an understanding of local ice actions and action effects. The engineering community has adopted the limit-state design methodology for offshore structures, however, adequate guidance on how to design a structure against an accidental limit state (ALS) due to ice actions is lacking. The majority of existing experimental and full-scale ice data come from the structures that are virtually rigid and thus may not be representative for the scenarios where the structure deforms. Floating-ice impacts in which the structure sustains damage are in the shared-energy regime – both the ice and the structure dissipate energy through inelastic deformation. When analysts consider the shared-energy approach for assessment of the structure’s capability to withstand glacial ice impacts, they should be aware of the variations in input data and of how they might affect their analysis. This study is a follow up of the response assessment of a hull structure under glacial ice impact loads. The paper examines the required information for application of the shared energy method, the variances in that information, and how these variances affect the assessment of structural performance. Results of analysis indicate that using the rule-based ice load models may be insufficient for damage assessment under the ALS caused by ice. It requires a case-tailored view on the energy absorption capacity of ice and ALS criteria.