Non-linear P-delta behaviour of three-dimensional frames with plan and elevation
asymmetries is studied, using a parametric variation of geometry in plan and a
stiffness variation along the height. Some behavioural aspects of a calibration frame
have been addressed to ascertain the importance of the nodal rigidity, modelled with
laminar elements of the type shell with implicit formulation of thick plate or
modelled with elastic stiff springs, in the study and modelling of the geometric nonlinearity
and stability of such calibration frame. Eurocode 3 criteria for second order
analyses is briefly addressed in connection with the 2D frame classification with
respect to sway behaviour; however for 3D structures the calculated carrying
capacity is independent of this classification. So a parametric study of the critical
load factor of asymmetric three-dimensional frames, un-braced and braced, permits
to characterize their carrying capacity with respect to overall structural stability
