The importance of allowing for the many different types of structural interaction that have an
effect on the performance of light gauge members when used in practical situations is
emphasised. A distinction is drawn between internal interactions involving the various plate
elements of the steel profiles and external interactions involving the other components in the
system. Although full-scale testing of representative systems can capture this behaviour, the
costs involved make this an impractical general basis for design; codified methods generally
consider only isolated plates within members and isolated members within systems, thereby
neglecting the potentially beneficial effects of both forms of interaction. Properly used,
modern methods of numerical analysis offer the potential to systematically allow for both
forms of interaction – provided the numerical models used have been adequately validated
against suitable tests. The use of such an approach is explained and illustrated for three
commonly used structural systems: roof purlins, floor beams and columns in stud walls. In
each case it is shown that, provided sufficient care is taken, the numerical approach can yield
accurate predictions of the observed test behaviour. The subsequently generated large
portfolio of numerical results can then provide clear insights into the exact nature of the
various interactions and, thus, form the basis for more realistic design approaches that are
both more accurate in their predictions and which lead to more economic designs. Building
on this, modifying existing arrangements so as to yield superior performance through specific
modifications is now possible. Two such examples, one in which improved interconnection
between the components in a system is investigated and a second in which prestressing is
shown to provide substantial enhancement for relatively small and simple changes, are
presented.