P-delta analysis

[MohammadZaman]

Hello.

I want to take account p-delta effects in DL+LL combination and modified stiffness matrix under this combination and take effects of p-delta to other combinations (Like buildings code). Is there any option to do this?

Thank you.

[Pawel.Pulak · Accepted solution]

It is not quite clear what you want to do.

1/ If you want to assign or modify nonlinear p-delta analysis to several load cases and combinations then it can be done using the bottom part of Analysis Type window:

2/ If you want to use some nonlinear combination as the starting condition for other load cases (incrementing load basing on some already applied load) it is not possible to use combination as a starting case. Only the first simple case can be used as the starting one - see the screen capture below.

The workaround is to use in the first simple load case all loads contained in the combination

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[amirdj.gc]

Hello,

i might be out of subject but i would really ask about how to view the P-DELTA analysis results in RSA.

[Pawel.Pulak]

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                  i might be out of subject but i would really ask about how to view the P-DELTA analysis results in RSA.

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There are no results specific for considering geometrical non-linear 2nd and 3rd order effects  in RSA ("Non-linear" and "Non-linear P-delta" in RSA settings) - the same results as for any static linear analysis are available.

The possible influence of non-linear geometrical effects  is in values of forces, moments, reactions and displacements comparing to static linear analysis results.

Some additional information and simple example can be found in  this forum post:

http://forums.autodesk.com/t5/Autodesk-Robot-Structural/Non-linear-analysis-P-delta-analysis/m-p/364...

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Regards

[structural.engineer79]

Dear Pawel 

what is the difference between them?

which type of analysis we change it to Pdelta analysis ? Its for simple case or for simple case and combination ? 

Thanks