Eccentricity strange results

Hello @karamba3d experts,

I was trying to compare 2d frame analysis with karamba and RSTAB. I have attached both the files below. The middle beam of the frame undergoes eccentricity. I tried to replicate the local axis in Karamba the same as that of RSTAB. All other material and cross-section properties are also the same. Even the hinge and loads added are the same. I obtain the SAME maximum displacement, support reactions. However, there is a vast difference in the normal force and I find some difference in shear force as well. The results seem strange to me. When I remove the eccentricity in both the software. All the results of internal forces turn out in Karamba as that of RSTAB. It’s somehow strange how Karamba deals with the eccentricity and is not clear to me. Could someone explain, please? I am curious to know.

Below are images of RSTAB and Karamba presenting normal forces.


Here is the Karamba file:
frameecc.gh (61.8 KB)
I couldn’t upload RSTAB file here, so i have a DSTV export of it uploaded.
frame3_ecc.stp (5.7 KB)

Regards,
Veronika Phadtare

Could someone please explain on this please :slightly_smiling_face:? Would really appreciate the help.

Hi Veronika,

that is strange, when I open your script it shows me the same values as your first image (from RSTAB).
This was checked on version 1.3.3. of Karamba

Hello Matthew,

I appreciate you help. Well it is strange. I use Karamba 1.3.2. Moreover, I was obtaining such strange results for axial forces for different systems that I tried . Till now I have been doing all my analyses with Karamba 1.3.2. I am curious, can you share what could be the possible reason for it please?

Regards,
Veronika Phadtare

Hello @veronika.phadtare,
sorry for the inconvenience.
There is a bug in Karamba3D 1.3.2 regarding eccentricities (see here, last paragraph).
– Clemens

Hello @karamba3d,

Thanks a lot for this information.

Regards,
Veronika