phase 4 report - DNV

RN02: DESIGN OF FLOATING STRUCTURES IN ICE // PART 4 ANNEX ABarents 2020Besides the parameters used in Equations (A.8-25) and (A.8-26), the following parameters are used in the twomodels, with the various parameters expressed in consistent units:H Bis the horizontal action on the cone due to ice breaking;V Bis the vertical action on the cone due to ice breaking;H Ris the horizontal action on cone due to ride-up;V Ris the vertical action on cone due to ride-up;σ fis the flexural strength of the ice sheet;h is the thickness of the ice sheet;w is the waterline diameter of the cone or width of a sloping structure;ρ iis the density of ice, see A.8.2.8.10;ρ wis the density of water;g is the acceleration due to gravity;ν is the Poisson ratio for ice, typically equal to 0,3.The flexural strength depends on the size of the ice specimen that is used to obtain this parameter. Therefore, thevalues of this parameter should be adopted from field tests where the specimen size is comparable to the designcondition (see A.8.2.8.3).For the case of sheet ice moving against a downward sloping structure, ice bending failure is initiated and thebroken ice is pushed down the slope (see Figure A.8-N). The distance moved by the broken ice down the slopeis limited by the downward extension of the shaft (if existent) or by the draft of the vessel and will depend onthe slope angle, ice-piece size, friction and slope width. Information of ice transport along the underwater partof the hull is important in preventing excessive underwater rubble pile formations, for example, on appendageswhich will affect the global load on the structure.Note that for slopes exceeding slope angles of about 60 degrees, the ice load can revert to crushing failure whichwill be associated with increased ice force levels. Steep slopes are not recommended in the waterline area.Figure A.8-11 – Ice action components on a sloping structure for a two-dimensional conditionReport no 2012-0690 85