Model tests of four-legged jacket platforms in ice: Part 2. Analyses and discussions

Two series of model tests with cylindrical and conical models were performed to investigate the dynamic ice loads and the consequently structural responses on two types of four-legged jacket platforms. The test techniques and the experimental results are described in a companion paper. This paper provides analyses and discussions on the dynamic ice load and structural response behaviors. Analyses of the pile tests showed that both velocity and stiffness dependencies were predominant during ice-structure interaction. Violent vibrations were analyzed to be excited by ice when the interaction coefficient fall in the range of 18–28. Further discussion results showed that the nonsimultaneous effect of ice failures and the resulting dispersions of vibrating energy led this range being narrower for multi-pile structures. Analyses of the cone tests indicated that the nonsimultaneous effect and the subsequent breaking process led the exciting energy of ice loads almost uniformly dispersing in a wide frequency range, and only nonlinear resonances of the structure could be excited under such forcing loads. The comparison between the two test series showed that the amplifications of foundation reactions were higher in cone tests than those in pile tests, although ice load and structural response levels were much lowered by introducing cones fixed to platform legs at the water level.