ssc-367 - Ship Structure Committee

shall have sufficiently fine mesh and member properties to ensure
accuracy of the results. On other floating structures,such as the
TLP and a semisubmersible,the diaphragm action of the deck plating
can be represented either by shear plates or by equivalent beams.
5.2
FLOATING MARINE STRUCTURES
Both mobile and stationarymarine structures are discussed in this
section. The overall discussion is applicable to configurations
ranging from ships and barges to semisubmersiblesand tension leg
platforms (TLPs).
The floating marine structure configuration and the mode of
operation (mobile versus stationary) are the primary variables
affecting the development of an appropriate “loads” or
“hydrodynamics”model. The problems encountered and the technique
applied to determine the wave loads are different for ships and
other stationary marine structures for several reasons:
●
While ships are treated as slender bodies, most offshore
structures other than FPSOS, FOSS and drillships can not be
treated as slender bodies.
●
The three-dimensional flow calculation technique can be
appliedto typicalstationarystructuresbut cannot be applied
to ships that have a constant forward speed.
●
Steady-state response of a stationary structure to
excitationalwave loads allowsdeterminationof relativewater
particle velocities and accelerations and assessment of
structurecompliancy (netloading). These excitationalloads
have less influence on ships in-motion (i.e., near-complete
compliancy).
●
Stationaryfloatingmarine structuresaremoored/tethered and
are subjectedto low-frequencydrift forces,which, due to the
5-4