Limit mechanisms for ice loads on inclined structures: Local crushing

• Published in: Marine structures 2019-09, Vol.67, p.102633, Article 102633
• Main Authors: Ranta, Janne, Polojärvi, Arttu
• Format: Article
• Language: English
• Subjects: Algorithms; Arctic engineering; Buckling; Computer simulation; Crushing; Deformation; Discrete element method; Failure; Finite-discrete element method; Ice loads; Ice mechanics; Ice-structure interaction; Limit load; Load; Loads (forces); Offshore; Offshore engineering; Offshore structures; Peak load; Probability theory; Sea ice; Stochasticity; Two dimensional models
• ISSN: 0951-8339; 1873-4170
• DOI: 10.1016/j.marstruc.2019.102633

This paper focuses on mechanisms that limit the sea ice loads on offshore structures. It introduces a probabilistic limit load model, which can be used to analyze peak ice load events and to estimate the maximum peak ice load values on a wide, inclined, offshore structure. The model is based on simple mechanical principles, and it accounts for a mixed-mode ice failure process that includes buckling and local crushing of ice. The model development is based on observations on two-dimensional combined finite-discrete element method simulations on the ice-structure interaction process. The paper also presents a numerical limit load algorithm, which is an extension of the probabilistic limit load model and capable of yielding a large number of stochastic peak ice load values. The algorithm is compared to simulation-based and full-scale observations. Analyzing peak ice load events is challenging as sea ice goes through a complex mixed-mode failure process during such events. The algorithm is an effective tool for this analysis, and it shows that distinguishing between the buckling and local crushing failure is virtually impossible if the only data available from a peak load event is the value of the peak ice load. The algorithm shows potential in improving estimates of maximum peak ice load values on offshore structures. •We introduce a model for analysis of maximum ice loads in ice-structure interaction process.•The probabilistic ice load model is based on ice mechanics and simulated interaction processes.•Model accounts for mixed-mode ice failure including buckling and local ice crushing.•Model is extended into a numerical limit load algorithm for generating stochastic ice load data.•Results from the model are analyzed, discussed and validated against full-scale observations.