Impact from ice floes and icebergs on ships and offshore structures in Polar Regions

The principles for ULS design and ALS design for offshore structures are discussed. The use of pressure-area curve versus force-area curves for analysis for estimation of ALS impacts is deliberated. Aspects of local and global shape of the ice feature are discussed in view of external mechanics (demand for energy dissipation) and internal mechanics (local damage). Simplified methods for structural damage assessment are reviewed for ice loads that may move both transverse to and along the shell plating. Material modelling of ice for nonlinear finite element analysis (NLFEA) of ice-structure interaction is reviewed. The material models must be calibrated against design curves and the sensitivity of the material parameters with respect to mesh size is investigated. Results from simulation of impacts of ice with different shapes on the column of a floating platform are presented, and the critical shape for penetration of the front plating for the present structural configuration is identified.