Global Design Ice Loads’ Dependence of Failure Mode

Abstract

This paper addresses the prediction of global design ice loads on offshore structures related to the structural width. Fourteen events from full-scale measurements on the lighthouse Norströmsgrund are analysed to find out how the effective width should be taken into account for estimation of ice forces. Simultaneous failure is found during ductile crushing and static loading with drift speed/ice thickness (v/h) ratio from 0.001 to 0.05 1/s. Brittle crushing of level ice is found in events with v/h in the range of 0.2 to 0.4 1/s. During brittle crushing of level ice, both non-simultaneous and a quasi-simultaneous failure mode occurs. From this work, it is indicated that care should be taken in reducing the effective width when calculating design ice loads. KEY WORDS: ice load; zonal failure; structural width; simultaneous; quasi-simultaneous; non-simultaneous.