How to get the displacement under a load bigger than critical load

[Lirock]

Hi,everyone:
After I do a bulking analysis, I got the critical load. But I wonder how can I get the displacement if I apply a load bigger than the critical value?

 

[DanRail]

This response assumes linear elastic analysis. If you're doing a post-failure plactic analysis then please disregard this post

The idea behind bucking failure is that the structure becomes unstable if a load higher than Pcr is applied.

If the structure is unstable, then by definition the post-buckling deflection is undefined.

Picture a long column, like a 20' long piece of 1" pipe. For a non-eccentric load, below the critical buckling load, lateral deflection of the pipe is essentially zero. Once the pipe buckles, the deflection keeps increasing until the load is on the floor.

-Dan