ssc-367 - Ship Structure Committee

h. The fatigue life may -be modified to include the effects of
corrosion pitting in caissons. Corrosion pitting produces an
SCF at the location of the pit. The SCF is calculated as:
SCF=~+—
3 (:)
(1-# (1-$2
where:
b = plt depth
t
= nominal caisson thickness
The new life including corrosion damage is calculated as:
Old Life
New Life =—
(SCF)3
This estimate of fatigue damage can, if necessary, be refined by
consideration of the number of wave occurrences for different
directions and evaluation of the damage at a number of points
around the circumference of the member.
0.7. EXAMPLE PROBLEMS
0.7.1 Avoidance of Wind-Induced Cross-Flow Vortex Sheddinq
It
can be shown that for a steel beam of circular cross section, the
following relationship holds:
where:
c. Vrn~ W.
v r— ]4
cr = ‘W+WJ
(L/d)2 0 1
v cr =
critical wind
for the onset
shedding
velocity of the tubular necessary
of cross-flow wind-induced vortex
D-17