Nonlinear & Stability analysis of composite structures

In linear static analysis, composite stages may be simply taken into account by calculating each load case separately with the appropriate stiffness values. Internal forces and displacements are then combined after the analysis by simple summation.

In the case of nonlinear and stability analysis, load cases are combined beforehand and the calculation is run in one pass, with a single set of stiffness values. Because of that constraint, a reference composite stage must be selected to determine the appropriate set of stiffness values.

Composite nonlinear analysis

In the case of nonlinear analysis, the user may either select manually the reference composite stage or let the program select it automatically. The latter is the default behaviour. This can be configured in the properties of each nonlinear combination:

Automatic selection is based on the principle, that the last applied load case, in time, is relevant. For each nonlinear combination,SCIA Engineer considers the composite stage defined for each load case in that combination.

If the load cases in the combination are in composite stage...			Then the nonlinear combination is considered in composite stage...
Construction	Final, long term	Final, short term
X			Construction
(X)	X		Final, long term
(X)	(X)	X	Final, short term

In case a nonlinear composite analysis is carried out, the selected composite stage is listed for each nonlinear combination in the nonlinear calculation protocol. In case automatic selection is used, this allows checking which stage was actually used.

Composite stability analysis

In the case of stability analysis, only automatic selection is possible (see description above). The calculation protocol of stability analysis shows which composite stage was used for each stability combination.