Baltic model of global ice forces on vertical structures

This paper proposes a simple equation for the determination of the global ice pressure in a condition where competent level ice is acting on a vertical offshore structure. Full-scale data that was obtained on a lighthouse in the Baltic Sea was used in an investigation of local and global ice forces. The ice thickness and the aspect ratio are used as two independent parameters to account for the size effect. The proposed formula also takes account of the time of exposure and the differences that are met in ice forces in various ice regimes. Furthermore, two kinds of magnifying effects are considered. Based on existing laboratory data, the global ice pressure is considered to be a function of the compliance of the structure. In addition, a dynamic magnification factor is adopted to justify a conventional design approach, where a quasi-static load is used as a substitute for the time-varying ice force.