Limit mechanisms for ice loads on inclined structures: Local crushing

Abstract

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.