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Structures with Cables

This section discusses the specification of undeformed orientations in the case of structures that include cables. Although it was noted in an earlier section that this complicated issues slightly, it should be emphasised that in the overwhelming majority of analyses where cables are used, the undeformed orientation of elements is again of no consequence, and the specification of the components of the V and W vectors is unnecessary.

This section begins with a discussion of why the presence of cables should complicate matters at all. It then proceeds to examine in some detail the two situations where the presence of cables means consideration of undeformed orientations is necessary and indeed essential. For the record, the two situations are (i) where a structure combines elements which are defined on cables with elements which are not on cables, and (ii) when specifying rotational boundary conditions in a model containing cables.

Note that the comments in this section apply equally regardless of whether you defined the cables in a structure explicitly yourself, or Flexcom automatically generated them when you defined a structure with lines. As noted previously in the section ‘Lines’, Flexcom automatically determines whether a line should be modelled using a straight section or a cable based on the length of the line and the straight line distance between its start and end locations. So if you know Flexcom is going to use a cable or cables, you may occasionally need to consider the issues discussed here.

Further information on this topic is contained in the following sections:

•Why Cables Introduce Complications

•Mixing Cable and Rigid Elements

•Rotational Boundary Conditions and Cables