15 August 2002
SCOPE. This section presents criteria on structural design of drydocks,
with particular reference to dead loads, hydrostatic pressure, earth pressure, live loads,
special conditions of loading, materials and design stresses, and methods of analysis.
DEAD LOADS. Dead loads are of special significance because the
deadweight of the structure, including all mobilizable earth weight plus friction and
holddown piles, must be greater than the maximum buoyancy.
Weight of Concrete Structure. For design purposes, compute the
weight of reinforced concrete structures on the basis of 2403 kg/m3 (150 lb/ft3) (weight
Weight of Earth
. In computing the total resistance
to uplift, include the
weight of earth engaged by any extension of the slab beyond the outside of the wall.
Earth below the drydock floor, when engaged by holddown piles or other devices, is
included in the computation of the total weight.
Specific Weights. Unless special, lightweight soils are encountered, use
961 kg/m (60 lb/ft3) for submerged soils and 1602 kg/m3 (100 lb/ft3) for soils above
Computation of Volume. To compute volume with a dock empty and
with mean high water, use the soil weight above the slab projection between a vertical
plane at the outer edge of the projection and the back of the wall. With a dock empty
and extreme high water, add the weight of earth wedge between the vertical plane and
an intersecting plane sloping 15 degrees outward from the vertical plane.
Weight of Earth Engaged by Floor Slab Holddowns
Specific Weights. This earth is always submerged. For ordinary soils,
use 961 kg/m3 (60 lb/ft3.) Since this weight is usually very important, determine the
correct weight by test if there is any indication that the soil may be of a greater or lesser
Computation of Total Weight. The holddown capacity of individual piles
may be computed by methods given in DM-7.02 Foundations and Earth Structures.
The total holddown capacity is not necessarily the sum of the individual capacities of a
pile group and may never be larger than the weight of the block of soil included in the