ABSTRACT

In this study, the ice loads on conical structures obtained by three methods, the experimental ice loads obtained by an ice tank experiment, a theoretical method proposed by Ralston and a numerical method proposed by one of the authors are compared. It is concluded that the present method can estimate the ride-up component more realistically than the Ralston's equation does. And this results in a better agreement with the experimental ice loads. Above all, it is concluded that the proposed method can give a better simulation of the total ice loads on a conical structure.

INTRODUCTION

A conical shaped arctic structure is seemed to be one of the most basic shapes for arctic structures. The conical shaped structure is considered to be a typical inclined structure which breaks an oncoming ice sheet by flexure. And failing the ice sheet by flexure needs less load than failing it by crushing. However, it is not expected that any perfect conical structure would be used in reality. Because it should give us a first look estimation of ice loads on any inclined structures, and may give us an idea to understand the ice loads on an inclined structure. Several theoretical works (e.g. Ralston, 1977, Croasdale, 1980) and many experimental works (e.g. Kato, 1986, Hirayama and Obara, 1986) have been conducted on ice - cone interaction. Among them, it is no doubt that the Ralston's theoretical work is superb in terms of estimating ice loads on a conical structure in a simple manner. He considered three components of ice loads on a conical structure. They are a component to break the ice (the breaking component), component due to rotation of broken ice piece (the foundation component) and component due to ice pieces riding up onto the cone (the ride-up component).

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