Good evening dear community,
As you can see i study the behaviour of a crude oil skid when it is in service. In the first photo, you can see the skid as it is constructed in AUTOCAD PLANT 3D.
On the second one, I simulate loads of the piping with one vertical load (weight only when the pipe is full of product). On the 3d one I simulate the same piping loads but in 3 axes with the rule of thumb of friction load=0,4xvertical load and lateral load=0.1xvertical load.
The system is under the wind, seismic loads and their combinations as well.
After the model analysis and during the post-processing workflow, I see that with the vertical only loads, my model succeeds (4th photo) whereas, in the second scenario and 3-axis forces, a lot of beams are failing...(5th photo)
1st photo
2nd photo
3d photo
(same situation with 3rd but support is isolated in order the view to be clearer regarding the 3-axis forces
4th photo
5th photo
Which option is the best to follow for better and more realistic results? 2nd option and 3-axis forces are over-engineering results?
Thank you very much in advance for your support!
Kind Regards,
I see that the members are failing due to check cl. 6.2.7(5) which is usually triggered when there is some torsion on the member. This clause refers to the eq. 6.1 of EN 1993-1-1:2005 which is the yield criteria and leads to conservative results. You can find a discussion on this topic here: STAAD: Torsional design - Euro design code - RAM | STAAD Forum - RAM | STAAD | ADINA - Bentley CommunitiesIf the torsion loads are small on those failing members, I think you may use a Torsion 3 design parameter to ignore this yield criteria check as per eq. 6.1.