Loads needs to be considered during ship structure analysis

 

·         Loads needs to be considered during ship structure analysis:




1. Hull Girder Loads consist of wave-induced and still water loads on the hull girder. This
load should be considered for longitudinal structure in the main hull, and for the
interaction of a long continuous deckhouse (superstructure).

2. Hydrostatic Loads are pressure loads due to fluids. The pressure could be either
internal or external. Examples of hydrostatic loads are external pressure of the bottom
and sides of shell plating, and internal pressure in tanks and on watertight bulkheads.

3. Hydrodynamic Loads consist of liquid sloshing in tanks, shipping of green water on the
weather deck and impacting on the house front, and wave slap on all exposed structure
and equipment above the waterline, etc.

4. Live Loads consist of uniform deck loading, concentrated loads such as forklift or
aircraft landing and parking loads, support reactions from stanchions and equipment,
cargo container reactions, etc.

5. Dead Loads consist of the weight of the structure.

6. Ship Motion loads consist of inertial forces that act on the entire ship and are important
design loads for masts and topside foundations, such as topside cargo attachments.
The effect of ship motion loads on the hull girder is to produce vertical and horizontal
bending moments and torsion. A lengthy analysis is required to determine these values
for a particular ship and service characteristics

7. Shock Loads consist of displacements, velocities, and accelerations in all three
directions. This load is important for naval ships in the design of vital equipment and
their foundations, and ship structure in the vicinity of these foundations.

8. Missile and Gun Blast Loads consist of transient pressure and thermal load for all
structures within the blast impingement area; usually, a static equivalent pressure is
used.

9. Nuclear Overpressure consists of the transient traveling pressure waves from a nearby
nuclear air blast; this is an important consideration in the analysis of deckhouses
(superstructures).

10. Vibratory Loads consists of cyclic loading from rotating machinery, especially from
propellers, low-frequency full girder response from slamming and springing can also be
significant.

11. Thermal Loads are caused by heat inputs
    a. from solar radiation
    b. exhaust impingement from stack gases
    c. operation of machinery, especially combustion engines (important to deckhouses
    and exhaust ducting), diesel generator foundations, and condenser foundations

12. Environment loads consist of wind, snow, and ice loads.

13. Impact loads consist of displacement or velocity in all three directions.
A description of the boundary conditions applied to the model, and the reasons for the approach
adopted should be described. The description should include, but not be limited to, a discussion
of:
    a. model symmetry, antisymmetry, and axisymmetry
    b. material property changes at the boundary
    c. stiffness changes at the boundary
    d. assessment of influence on results of assumptions made concerning boundary conditions

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