By loadout, we mean the process of moving a structure
from a set of skidways on the land to a cargo barge. Normally,
the barge is placed some fixed distance away from the land skidway
and the structure is skidded along the land skid. At some point,
part of the structure will cantilever over the gap between the barge
and the land. The structure is moved further until part of it is
over the barge. At this time, the barge ballast is changed so that
the barge partially supports the structure. Now, the structure is
skidded further off of the land and onto the barge. Throughout
this process two things are important:
- The ballast in the barge, and
- The stresses in the structure.
These two things are intimately related. Even if the structure is
completely on the barge, it is possible to ballast the barge so
that the structure becomes overstressed.
Instead of considering the problem as a single difficult one, it
is normally separated into two problems:
-
Analyze the structure with a set of stiff supports which model
the barge skidways, the land skidways and the gap between the
two.
-
Design a barge ballast plan for the loadout so that the barge
has zero deflection when the reactions of the first analysis
are applied to it. The barge ballast condition must be computed
for quite a few intermediate positions between when the barge
first picks up load, and when the structure in completely on
the barge.
Since the barge has essentially zero deflection under the reactions
computed assuming zero deflections, the results of the two analyses
should be comparable. At the conclusion, however, one should check
a point or two to make sure that nothing was omitted.
