The action of long multi-year ridges on upward sloping conical structures

• Published in: Cold regions science and technology 2018-10, Vol.154, p.166-180
• Main Authors: Croasdale, Ken, Brown, Tom, Li, George, Spring, Walt, Fuglem, Mark, Thijssen, Jan
• Format: Article
• Language: English
• Subjects: Ice loads; Multi-year ridges; Sea ice; Sloping structures
• ISSN: 0165-232X; 1872-7441
• DOI: 10.1016/j.coldregions.2018.04.002

In ISO 19906 (2010), there are no algorithms provided for calculating loads on sloping structures due to interaction with multi-year (MY) ridges; only references are provided for a range of methods. A study was undertaken to review and improve the theories for MY ridge breaking and ride-up on a slope. This article reports on the new methods developed for long ridges which are defined as being long enough to develop both centre and hinge cracks. Short ridges, which are defined as being too short to develop hinge cracks, have also been investigated and new theories for short ridges are reported in an accompanying paper. The new method for long ridges includes a simplified approach for secondary failures of the hinge pieces which are successively broken as a ridge is pushed higher prior to rotation of the broken pieces around the structure. As well, for wide ridges, a new theory for failure across their width has been developed which leads to lower loads than if this failure mode is not included. Results using the new methods have been compared to tests conducted at the Imperial Oil outdoor ice basin in Calgary. These are the largest scale tests ever conducted in studying multi-year ridge loads on conical structures. A recommended methodology which includes closed-form equations for the various load components is presented. The method is considered suitable for inclusion in probabilistic methods and in future code developments. In this paper, examples of deterministic loads on typical Arctic structures are given. Continuing uncertainties are discussed and recommendations are made to address them. •Closed-form equations are developed for the action of long multi-year ridges on sloping structures.•The method includes sequential hinge crack failures as well as failure across the width of the ridge.•The method also accounts for clearing of the level ice ahead of the ridge.•The theory is compared with physical data from large outdoor ice basin tests.