Hi !

I am getting confused with the beam efforts orientation.

It appears that the cross section axis are not aligned with the 1D Element efforts axis.

As you can see on the deformed model, the cantilever beam axis are not aligned with the M1 and M2 moments whereas they are supposed to be calculated on the cross section major and minor axis.

Does it mean the 1D element effort are not calculated in the cross section principles axis ?

Thank you in advance,

Regards

Hey,

the cross section shows the orientation after deformation and cannot be scaled. The moments are computed around the inititial local y- and z-axis for linear analysis.

Thank you Anna for your reply.

So, from what I understand, the cross-section twist displayed here is the accurate bending and twisting deformation, meaning the moments M1 and M2 are not calculated on the principles axis, as shown on the nonlinear analysis above.

One would then need to project these efforts on the principles axis “by hand”.

However, the cross-section orientation is purely visual, there is no way to obtain the y- and z- axis of the deformed section, so one cannot assess the angle of twist between the red and blue vector frames, so how can it be done ?

Thank you in advance,

Regards,

bending moments are related to the principal axes. The orientation is depending on the type of analysis. The equilibirum is found for the initial axes for linear analysis and in the deformed configuration (axes) for nonlinear analysis. So, no projection is needed.

The 1d result component returns the base vectors of the deformed configuration if the respective option is checked in the analysis. The initial one has to be constructed by yourself for linear analysis (local z-axis in the plane of global z-axis and the tangent or user input). It can be retrieved in LC 0 for nonlinear analysis. The twist angle is computed by comparing those two sets.