Answer:
SHAPE‑THIN provides the option to connect independent cross-section parts by means of null elements. Thus, you will get a gross cross-section, and this can be used for the design in RFEM or RSTAB.
Null Elements
It is necessary to assign a thickness t to each element. This value is the actual thickness of the cross-section part for the full transfer of the normal actions. Furthermore, the effective thickness t* controls the shear transfer for "artificial" coupling elements with the thickness of t‑=‑0. These null elements are used to create a shear connection between two elements that do not have a common node. The definition of a shear thickness t* > 0 is required for null elements that have no contact with normal elements (t > 0) along their entire lengths.
