Ice loading on Danish wind turbines: Part 2. Analyses of dynamic model test results

The present paper deals with ice loads on wind turbine foundations from large floating ice floes. Some newly developed procedures to estimate the extreme ice load and combined loads from wind with loads from ice are described. The procedures have been developed as a part of the design basis for two of the first large offshore wind farms in Denmark, and they have been further developed in a research project including ice model tests with cones and vertical cylinders at the National Research Council (NRC), Canada. The principles are included in the new “Danish Recommendation to Technical Approval of Offshore Wind Turbines”. The design procedures are an integrated part of a selected design philosophy, which also includes a procedure for defining a consistent set of partial safety factors for the various extreme load cases. For a partial safety factor for wind loads of 1.4 to 1.5 (as defined in the Danish standards), the partial coefficients for ice load should be 2.0 to 2.5, depending on the determining ice load case.