Author(s): Mauri Maattanen; Anita Nortala Hoikkanen; John Avis
Linked Author(s): Mauri Määttänen
Keywords: No Keywords
Abstract: Full scale ice force measurements were conducted through a joint Finnish industry project in 1984-87 with a conical test section at the Kemi-l lighthouse in the Northern Baltic. However, detailed data analysis results were not fully realized until late 1995, after a joint industry project with several North American oil companies. Kemi-I cone ice force data was analysed for average, maximum, standard deviation, peak: load distribution shapes, and frequency content. Different ice loading scenarios include level ice, rafted ice and first year ridges. The results give, for the first time, a clear picture of different ice failure and clearing modes for a full scale conical structure. Ice failure in full scale occurs in multi-modal fashion by bending, shearing, and crushing. Rubble pile formation in front of the cone is common. Its geometry and volwne were analysed. The measured ice force values were compared to existing theoretical model predictions. In general, the predicted loads are higher than those actually measured regardless of the rubble pile effect In particular, dependence to ice thickness is significantly lower. This knowledge of ice failure modes. data analysis results, statistical distributions. and validated theoretical models give means for the reliable design of economical conical offshore structures in ice infested waters.
Year: 1996