In my model (with cross-section type L-section), I obtain no My or Mz moment if I rotate the member by 45°. How is this possible?
Unsymmetric cross-sections, for example angles, have an inclination of the main axis. The main axis angle α describes the location of the main axes relative to the standard main axis system. For unymmetric sections, this is the angle between the axis y and the axis u. This angle is defined as positive if clockwise.
If a bending moment at an unsymmetric cross-section is determined, the designation of the bending moment changes to Mu and Mv, accordingly. For a member rotation of 0°, a moment Mu or Mv is shown in the output of internal forces. If you change the angle of the member rotation corresponding to the main axis angle of the cross-section, the member axis system u,v,w is rotated accordingly.
To influence this, you can activate the "Member Axis Systems u,v,w" in the display navigator. If the axes u or v run parallel to the load direction, the internal force Mu or Mv are omitted.