Ice force spectrum on narrow conical structures

This paper presents an ice force spectrum model for narrow conical offshore structures deployed in ice infested areas. The force spectrum is developed from a spectral analysis of ice load data that was obtained in full-scale tests on the JZ20-2 platform in Bohai Bay. The results show that the power spectral density (PSD) function of the ice force has characteristics of both a narrow band and a wide band random process when the ice sheets fail by bending and the broken ice pieces are totally cleared up. The PSD function of the ice force can be approximated by the Neumann spectrum. This spectrum is the basis for the ice force model that is presented in this paper. This model can be used in a dynamic analysis of narrow, conical offshore structures that are exposed to the action of drifting ice floes.