Capacity of ice-strengthened structures subjected to different ice-loading scenarios

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Journal Title
Journal ISSN
Volume Title
Insinööritieteiden korkeakoulu | Master's thesis
Date
2017-02-20
Department
Major/Subject
Mechanical Engineering
Mcode
IA3027
Degree programme
Master’s Programme in Mechanical Engineering
Language
en
Pages
55+28
Series
Abstract
This thesis investigates the critical loading scenarios of multiple ice-strengthened ship structures when subjected to different load configurations. Evaluation of structural performance has been conducted using Non-linear Finite Element Analyses. Using a non-uniform pressure patch (NUPP), the capacity of ship structures was investigated and the safety margins against different capacity levels was determined. Results show that the point of yield and load for permanent deformation are highest for a structure built with IA Super ice class of the Finnish Swedish Ice Class Rules (FSICR). The values are observed to decrease for weaker ice classes. Although the present approach of FSICR is to design structures to yield once per winter, the safety factor against yield was about two for ice classes IA and IB, but slightly lower for IA Super. Comparison of different loading approaches, namely present design approach and non-uniform pressure patch, show that the FSICR approach yields much stiffer response. This justifies the use of less conservative NUPP for structural capacity evaluation, results of which show that the present FSICR design approach is extremely conservative. Alternatively, the current design pressure patch approach renders structures more safe than they actually are. Therefore, future investigations must clarify the pressure profile due to the ice loads.
Description
Supervisor
Romanoff, Jani
Thesis advisor
Korgesaar, Mihkel
Suominen, Mikko
Keywords
winter navigation, Finnish-Swedish ice class rules, ice-strengthened structures, ice-loading scenarios, limit states, decreasing load function
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