Bug of the sectionForce command?

[xinyue]

I think there might be a bug in the sectionForce command. For dof=6 and dof=5, I'd expect to have Mz and My respectively. But it returns all 4 section forces. Please see the attached picture. Did anyone have the same problems before? Please correct me if I'm worng. Thank you.

https://www.dropbox.com/s/64hs83u61uz67 ... g.PNG?dl=0

[mhscott]

Why do you think Mz and My are 5 and 6?

https://portwooddigital.com/2022/11/04/ ... antilever/

[xinyue]

Why do you think Mz and My are 5 and 6?

https://portwooddigital.com/2022/11/04/ ... antilever/

Thank you very much for yuor reply and teaching me/us 'how to fish', professor. Just wanted to provide updates from my side in case that other people may find helpful. I figured this out by building a simple model with simple load following the post.

1.The numbering of the dof for the 'sectionForce' command is 1,2,3,4 corresponding to P, Mz, My and T respectively. If you put 5 or 6 which is not expected by the command, it will return all 4 forces (a bug? or maybe a trick?). This explains what I got in the screenshot. See this link for what dof are valid for your section: https://openseespydoc.readthedocs.io/en ... ction.html

2.This means that OpenSees doesn't always respect the traditional/typical numbering of dof (i.e., 3D, 6dof: Fx Fy Fz Mx My Mz). (Not sure if this is a good thing though...). Anyway, a safer way to figure this out is to use Prof. Scott's suggestion in the post he shared.

Thank you again.

[mhscott]

You are confusing section forces with nodal forces. They have separate numbering conventions.