Author(s): Mauri Maattanen

Linked Author(s): Mauri Määttänen

Keywords: No Keywords

Abstract: Scale model tests were conducted in order to find out ice force interaction effects in the case of a multi-legged structure having conical sections at the water-line. Either downward or upward breaking cones, having a slope of 61 degrees, were pushed by a car­riage to break fine grained model ice with 1:25 scale ratio. The varied parameters besides the ice velocity were the spacing of the cones and the direction angle of the triangular cone pattern in relation to ice movement. The results indicate partly similar trend as what have been learnt earlier with multi-legged vertical cylindrical structures. With decreasing leg spacing the total ice force first decreases but starts to increase again when leg spacing approaches one characteristic length of ice. At intermediate range the decreasing trend of total ice load is more pronounced due to stronger influence of cracks in bending than in crushing The same reason also explains the effect of the direction angle of the triangular cone pattern. As expected, the total ice loads in downward breaking mode are significantly smaller than in upward breaking mode. The results can be utilised in design, e. g. for extend­ing the operational season of a jack-up platform in marginal ice zone, by furnishing its legs with conical sections to reduce total ice loads.

DOI:

Year: 1992