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Upward load

Verfasst: Mo 9. Okt 2017, 13:35
von Anders_Kallenberg
Hi
When I use a contant hanger at a certain node, calculations are performed without problem. The constant hanger results show a lift of 9mm in specific load cases. But when I want to evaluate secondary steel and use an internal constant hanger, calculations are halted due to upward load in same hanger.
How can I fix this problem?

Regards
Anders

Re: Upward load

Verfasst: Do 12. Okt 2017, 10:31
von rohr2support
Hi

The problem may arise, if your structural steel has more deflection than your pipe.
Steel_Pipe_Internal.JPG
As the détermination of the "theoretical" weight distribution is based on rigid supports, the pipe would hold the structural steel and not the inverse. Therefore the automatic design proceedure will give you a warning about the "upward loads".

You should set the installation load of you constant hanger as a function of what you want to achive.
If you want no deflection at the constant hanger in the dead weight situation while the strutural steel to which it is attached has a significant deflection you may make a preliminary run with an additional vertical support (external support) in the structural steel at the attachment position:
Steel_Pipe_Interna2l.JPG
Then you fix the installation load and remove the temporary rigid support:
Steel_Pipe_Interna3.JPG
Now your structural steel has a huge deflection but the pipe is held in possition.

Do not forget to check stresses in your beams ...

Best regards

Rohr2 Support

Re: Upward load

Verfasst: Fr 13. Okt 2017, 09:04
von Anders_Kallenberg
Hi
Thank you, it works fine!
Regards
Anders