FAQ 001101 EN

Calculation RFEM RSTAB

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?

Answer

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.

RFEM Main Program
RFEM 5.xx

Main Program

Structural engineering software for finite element analysis (FEA) of planar and spatial structural systems consisting of plates, walls, shells, members (beams), solids and contact elements

RSTAB Main Program
RSTAB 8.xx

Main Program

The structural engineering software for design of frame, beam and truss structures, performing linear and nonlinear calculations of internal forces, deformations, and support reactions