4.27.1 Cargo containment systems that are of a
novel configuration that cannot be designed using sections 4.21 to
4.26 shall be designed using this section and parts A and B of this
chapter, and also parts C and D, as applicable. Cargo containment
system design according to this section shall be based on the principles
of limit state design which is an approach to structural design that
can be applied to established design solutions as well as novel designs.
This more generic approach maintains a level of safety similar to
that achieved for known containment systems as designed using 4.21
to 4.26.
4.27.2.1 The limit state design is a systematic
approach where each structural element is evaluated with respect to
possible failure modes related to the design conditions identified
in 4.3.4. A limit state can be defined as a condition beyond which
the structure, or part of a structure, no longer satisfies the requirements.
4.27.2.2 For each failure mode, one or more limit
states may be relevant. By consideration of all relevant limit states,
the limit load for the structural element is found as the minimum
limit load resulting from all the relevant limit states. The limit
states are divided into the three following categories:
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.1 Ultimate limit states (ULS), which correspond
to the maximum load-carrying capacity or, in some cases, to the maximum
applicable strain or deformation; under intact (undamaged) conditions.
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.2 Fatigue limit states (FLS), which correspond
to degradation due to the effect of time varying (cyclic) loading.
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.3 Accident limit states (ALS), which concern
the ability of the structure to resist accidental situations.
4.27.3 The procedure and relevant design parameters
of the limit state design shall comply with the Standards for the
Use of limit state methodologies in the design of cargo containment
systems of novel configuration (LSD Standard), as set out in appendix
5.