UFC 4-152-01
28 July 2005
3-4.8.2
Static Pressure.
Freshwater ice will exert less pressure on a structure than seawater ice of the same
thickness. For freshwater ice, assume pressures of 15 to 30 psi (103.4 to 106.8
kPa). For sea ice, pressures of 40 psi (275.8 kPa) to as much as 150 psi (1034.2
kPa) may be assumed. These are maximum values and relate to crushing of the
ice. If the ice sheet can ride up on the nearby shore, the pressure exerted will be
less than if the ice sheet is confined within vertical boundaries.
3-4.8.3
Slow Pressure.
Broken ice floes will exert less pressure than a solid ice sheet. In general, the
pressures developed in this mode of action will be less than those to be experienced
under the static pressure mode of action. Reliable values of pressure are not
presently available.
3-4.8.4
Vertical Movement.
Assume that the structure will lift or depress a circular sheet of ice. Calculate the
radius of the affected ice sheet on the basis of the flexural strength of ice as 80 to
200 psi (1379.0 kPa.) Check the shear on the basis of the strength (and adhesion)
as 80 to 150 psi (551.6 to 1034.2 kPa.) Consider the formation of bustle (added
thickness) of ice around the structure. See Ice Pressure on Engineering Structures.
3-4.9
Shrinkage.
Open pier and wharf decks, which are usually constructed from concrete
components, are subject to forces resulting from shrinkage of concrete from the
curing process. Shrinkage loads are similar to temperature loads in the sense that
both are internal loads. For long continuous open piers and wharves and their
approaches, shrinkage load is significant and should be considered. However, for
pile-supported pier and wharf structures, the effect is not as critical as it may seem
at first because, over the long time period in which the shrinkage takes place, the
soil surrounding the piles will slowly "give" and relieve the forces on the piles caused
by the shrinking deck. The PCI Design Handbook is recommended for design.
3-4.10
This is also a material-specific internal load similar to shrinkage and temperature
and is critical only to prestressed concrete construction. The creep effect is also
referred to as rib shortening and should be evaluated using the PCI Design
Handbook.
3-5
LOAD COMBINATIONS.
3-5.1
General.
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