1.1.1 This
Chapter explains the alternative procedure for load development. This
procedure provides more realistic loading scenarios, improving the
user's confidence in the loads which are to be applied to the finite
element model.
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This Chapter provides
guidance on:
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A method to derive
the design loads using direct calculation techniques. These loads
may be used instead of the Rule loads in all aspects of structural
assessment provided that the proposed loads are submitted and approved
by LR.
-
A method to apply
the Rule load value or direct calculation load value to the finite
element analysis.
1.1.2 Design
loads are to be determined (i) theoretically by using a suitable hydrodynamic
program and/or (ii) experimentally through model tests.
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The theoretical
procedure for developing wave-induced design loads acting on the structure
by a ‘first principles’ approach is specified in Vol 4, Pt 1, Ch 3, 2 Theoretical analysis.
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Details of the
model experiments required to be carried out are specified in Vol 4, Pt 1, Ch 3, 3 Model experiments. Results from full scale measurements
may also be acceptable.
1.1.3 Application
of design loads for structural analysis and verification is to be
carried out as follows:
-
Each design load
value is to be applied to the structural analysis by the application
of a characteristic regular wave which is associated with a particular
ship speed, heading, specific height H and frequency
ω determined using this procedure.
-
The corresponding
external pressures and inertial loads of the characteristic regular
wave calculated at a particular time instant are to be derived and
applied to the FE model to generate the design value.
1.1.5 Full
details of the scope of the analysis and the procedures to be adopted
are to be submitted and agreed with LR prior to commencement of any
analysis.