Selection of base load and perturbation load for linear buckling analysis

[flakyman]

Hi,
I am trying to decide what loading should be applied in base state and perturbation state while performing an linear buckling analysis as per Type 1 ASME Div 2. I understand that the base state represents the initial pre-load. My understanding is that if we are checking for a load combination P+Ps+D then the base state loading should be D only and P+Ps will be the perturbation loading because pressure is incremental load applied to the vessel. Is this approach correct?
My confusion started when I saw that the code says " In this analysis, the pre-stress in the component is established based on design load combinations (1) through (9)in Table 5.3." This line appears to say that the pre-stress should be established using P+Ps+D.
Any thoughts on this matter are appreciated.

TIA

 

[TGS4]

Please do not use the Edition of the Code that you are currently using for buckling analyses. The Code received a major update to the Buckling rules in the 2023 Edition - in part to deal with some of the issues/question that you are asking. Additionally, the eigenvalue buckling analysis is potential unconservative when the buckling stress exceeds 55% off yield.

So, my strongest recommendation possible is to restart your work with the 2023 Edition, and abandon the work that you are doing based on an earlier edition of the Code.

If you have any questions about the 2023 Edition analysis, please come back and ask.