Actions on wind turbines - Concrete Structures for Wind Turbines - page 81

Table 2.17 Bending strength of sea ice [24]

Return period [years] Bending strength of ice s B,k [MPa];

Designations simplified after [26]

Southern North Sea,
Skagerrak, Kattegat

Western and southern
Baltic Sea

5 — 0.25

10 — 0.39

50 0.50 0.50

100 — 0.53

The characteristic bending strength of ice s B,k governs for ice loads acting on the

inclined surfaces of structural members (Table 2.17).
In the case of raking piles, ice floes can be broken up by shearing or bending earlier than
the crushing of the ice. According to [26], the horizontal ice load due to drifting ice acting
on raking piles, irrespective of their cross-sectional form, is calculated as follows:
a) For a shear failure
F s ; k ¼ c fs

t ; k k tan b d h ½ kN

b) For a bending failure

F b ; k ¼ c fb s B ; k tan b d h ½ kN

where
c fs shape factor for shear failure after [26]
t k characteristic shear strength [MPa]
k contact coefficient, generally k ¼ 0.75
c fb shape factor for bending failure after [26]
s B,k characteristic flexural tensile strength [MPa]
b angle of inclination of pile from the horizontal (compression failure governs

when b> 80 , see above)

d width of single pile [cm]

h thickness of ice [cm]

The smaller ice load governs in each case. This is usually flexural tensile failure because
the shape factors are about one power of 10 smaller than those for shear failure.
According to [28], the compressive strength s 0,k , shear strength t k and flexural tensile
strength s B,k of sea ice are related as follows:

t k s 0 ; k = 6

s B;k s 0;k = 3

(compare Tables 2.16 and 2.17)