Author(s): T. G. Brown
Linked Author(s):
Keywords: No Keywords
Abstract: Dynamic Ice forces have been observed on a number of strucrures of widely differing shape and stiffness characteristics. Generally speaking, however, dynamics are only observed when ice is failing in a crushing mode and hence the structure is vertical, or near vertical. Considering the wide variety of structural forms and stiffnesses which have experienced dynamic ice forces, it is possible that the source of the dynamic behaviour differs from one structure to another. While it may be possible to design structures to avoid dynamics, it is important that the source of dynamic ice forces be thoroughly understood such that models may be developed to predict when dynamic ice forces may occur and determine their effect on the strucrure response. Previous work carried out by the author has provided some confidence that such modelling is possible, but these models lacked the generality which would permit them to be applied to different structures under different ice conditions. Specifically, certain parameters were fixed as part of the tuning process, on the basis of measurements obtained during acrual dynamiC ice interaction events. The modelling described in the present paper circumvents the specification of these parameters and permits the model to be applied, largely without restriction, to any form of vertically sided struCU1re in virtually any ice conditions. The parameters which require to be specified are then only parameters which are characteristic of the given ice conditions: type, temperature, thickness, grain structure, and rheology. The proposed approach shows considerable promise as will be shown by some of the preliminary results obtained. The proposed model is based on a damaging behaviour of intact ice under plain stress or plain strain conditions, and extrusion behaviour of crushed ice which results from the pulverization of highly damaged intact ice. It is shown that the dynamic characteristic of the ice load can be explained through the material behaviour of these two components and that the strucrural response (as illustrated from measured responses of the Molikpaq in 1986) are appropriate responses to the ice force variations.
Year: 1994