Scale Effect in Ice Flexural Strength

Abstract

Ice flexural strength is an important parameter in the assessment of ice loads on the hulls of ice-class ships, sloped offshore structures, and sloped bridge piers. While scale effects in compressive ice strength are well known, there has been debate as to the extent of scale effects in ice flexural strength. To investigate scale effects during flexural failure of both freshwater and saline ice, a comprehensive up-to-date database of beam flexural strength measurements has been compiled. The database includes 2073 freshwater ice beam tests with beam volumes between 0.00016 and 2.197 m3, and 2843 sea ice beam tests with volumes between 0.00048 and 59.87 m3. The data show a considerable decrease in flexural strength as the specimen size increases, when examined over a large range of scales. Empirical models of freshwater ice flexural strength as a function of beam volume, and of saline ice as function of beam and brine volumes have been developed using regression analysis. For freshwater ice, the scale-dependent flexural strength is given as: σf=839(V/V1)−0.13 For sea ice, the dependence of flexural strength has been modeled as: σ=1324(V/V1)−0.054e−4.969vb. Probabilistic models based on the empirical data were developed based on an analysis of the residuals, and can be used to enhance probabilistic analysis of ice loads where ice flexural strength is an input.