First define which type of structure it is:
Space type:
is the structure where the geometry , loading cause the structure to deform in all 3 global axes (X, Y and Z).
Plane type:
is the structure where the geometry , loading and deformation is restricted to global X-Y plane only.
Floor type:
is the structure where the geometry is confined to the X-Z plane.
Truss type:
is the structure carries loading by pure axial action.