Answer:
The reason for the occurrence of bending moments in inclined and straight girders is that the central column has a certain flexibility due to its finite stiffness. Thus, a compression occurs on the central column so that the deformation of the central column also affects the right beam. Since the right beam is additionally supported by a moving support, an axial moment is created at this location.This is especially evident from the respective deformations (see Image 02).
The deformation encircled in Image 2 is decisive for the formation of the bending moment in the right part of the structure.
The calculation using RFEM results in minimum bending moments, which are, however, not considered in the manual calculation (see Image 03).
