Author(s): P. R. Kry
Linked Author(s):
Keywords: No Keywords
Abstract: When an ice sheet moves past a wide structure, the ice failure mechanism is characterized by an irregular contact zone and non-simultaneous failure across the width of the structure. Where sufficient ice motion occurs to prevent formation of a frozen bond between a structure and an ice sheet, this failure mode becomes the design condition for ice crushing against the structure. Due to the nature of the failure, the effective stress across any local region of the failure interface is an irregular function of the ice sheet motion. This observation is developed into the concept of independent zones of crushing in front of a wide structure. It is assumed that as the ice sheet moves past the structure, effective stresses for each zone are developed independently of those in adjacent zones. In each zone, stresses are characterized statistically by the probability of exceedance of a stress level and the mean continuous duration of that exceedance. A statistical summation is used to calculate risk of stress exceedance as a function of stress level and extent of ice movement over the anticipated life of the structure. The use of ice sheet thickness to scale ice sheet displacement is advocated. A design stress can be defined by the level of risk of stress exceedance which is acceptable in a particular instance. Published data is used in example calculations to demonstrate the reduction in design stress derived from a conventional extrapolation of the data.
Year: 1978