Crushing Ice Forces on Structures

Abstract

On the basis of the results of small-scale and medium-scale indentation tests and full-scale measurements of ice forces, a methodology to estimate crushing ice forces is presented. The main point to note is that the effective pressure depends on the relative indentation speed, which in turn depends on the speed of a moving ice floe and the compliance of a structure. An increase in indentation speed leads to a change in failure mode from ductile to brittle, resulting in decreased effective pressure, and vice versa. The ice forces also depend on the temperature of the ice, because its strength and brittleness increase with decreasing temperature. The two codes for bridge piers and offshore structures are valid for brittle crushing of ice at high indentation speeds, and the recommended design effective pressure from these two codes is the same for wide structures (or large contact area) but differs for narrow structures (or small contact area).