# Nonlinear Static Analysis : Modelling Implications
# Cases
The principle of superposition is not valid for non-linear behaviour so unlike linear static analysis, results from different analyses must not be added together. An analysis case can be defined as the summation of factored load cases. This total loading is then analysed. Combination Cases formed from previously analysed Gss, non-linear or GsRelax results will probably contain invalid results. Combination Cases should only be used for producing envelopes in these cases.