P-Delta effect not considered for dilatation load case

[aa_aus]

I am applying loads due to special load as dilatation in robot. I have two issues. the software some not able to account for P-delta second order effects. The self-wight cause bending and deflection that shall increase due to compression force from the actions applied as dilatation.

Also, the steel design, i cannot seem to be able to get the software to calculate the buckling parameter although I have defined this I think properly.

see attached images.

[CaioSaporito]

Hi @aa_aus!

You put retraction instead of dilatation  and this cause tension on bar. That's why Robot doesn't consider buckling parameters in calculation.

Best regards, 

Caio

[aa_aus]

Thanks. The deflection seems to work now but the software still not show the extra bending moment due to P-delta for the deformed shape

[CaioSaporito]

In my opinion there is no p-delta effect in this model since there is no displacement in direction Z global  at the end of bars (supports). The addition bending moment (Dilatation force  X dZ) doesn't exist.

Anyway, I don't know if you really activated P-delta, so see this image below.

Best regards,

Caio

[CaioSaporito · Accepted solution]

Another thought:

I think you wanna count with "small p-delta" instead of p-delta. 

Maybe this thread can help:

https://forums.autodesk.com/t5/robot-structural-analysis-forum/geometric-non-linear-analysis/td-p/44...

" In the current version of Robot only P-∆ is implemented. The P-δ can be accounted for by defining some nodes along the bars" 

[aa_aus]

Thanks a lot. This is now working. I am using another FEA software and results now matching.