4

Wwater = - [pi]R3[UPSILON]

3

where

Wwater = weight of water, lbs

R = inside radius of sphere, feet

[UPSILON] = density of seawater, lbs/ft3

4

thus

Wwater = - [pi] (7.5)3 (64.0) = 113,100 lbs.

3

The weight of the sphere (neglecting penetrations) is calculated by

Wsp = 4[pi](r)2 (tsp ([UPSILON])

where

Wsp = weight of sphere, lbs

r = mean radius of sphere, inches

[UPSILON] = density of steel, lb/in.3

Thus

Wsp = 4[pi](91.0)2 (2.0)(0.283) = 58,900 lbs.

Assume that the penetration reinforcements and entranceway, etc., add

another 10,000 lbs of dead weight load to the structure. Thus the total

dead weight load to be sustained by the cylindrical support skirt is

Wtotal = 113,100 + 58,900 + 10,000 = 182,000 lbs.

(5) Support Skirt Compressive Stress.

The average compressive

stress in the support skirt is given by

Wtotal

[sigma]comp = ------------

[pi]Dsts

[sigma]comp = compressive stress, acting longitudinally in the

support skirt, psi

Ds = mean diameter of skirt, inches

ts = thickness of support skirt

Wtotal

solving for ts

ts = ---------------------

[pi]Ds[sigma]comp

and arbitrarily*

setting [sigma]comp = 2,000 psi

182,000

ts = ------------------- = 0.241

[pi](120.0)(2000.0)

set ts = 0.25 inches.

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