Section VIII, Div 2 Part 5 Design by analysis. Protection against buckling clarification
Section VIII, Div 2 Part 5 Design by analysis. Protection against buckling clarification
(OP)
Hi,
I am performing buckling analysis of a vessel according to Part 5.4. The design load factor to be achieved is calculated from a capacity reduction factor. I am specifically looking at ellipsoidal head. The capacity reduction factor mentioned in the section 5.4.1.3 is only for ellipsoidal head with external pressure. Following are the two questions in this regard.
1) What about the buckling of the ellipsoidal head knuckle. Is there a different capacity reduction factor for the head knuckles which are in danger of buckling under internal pressure?
2) I believe the capacity reduction factor is for a complete collapse of the head. How should local buckling be treated e.g local buckling due to nozzle loads. Is the same capacity reduction factor valid for local buckling.
Any insight into these issues are greatly appreciated.
Thanks and Regards,
Jaspreet Hothi P. Eng
I am performing buckling analysis of a vessel according to Part 5.4. The design load factor to be achieved is calculated from a capacity reduction factor. I am specifically looking at ellipsoidal head. The capacity reduction factor mentioned in the section 5.4.1.3 is only for ellipsoidal head with external pressure. Following are the two questions in this regard.
1) What about the buckling of the ellipsoidal head knuckle. Is there a different capacity reduction factor for the head knuckles which are in danger of buckling under internal pressure?
2) I believe the capacity reduction factor is for a complete collapse of the head. How should local buckling be treated e.g local buckling due to nozzle loads. Is the same capacity reduction factor valid for local buckling.
Any insight into these issues are greatly appreciated.
Thanks and Regards,
Jaspreet Hothi P. Eng





RE: Section VIII, Div 2 Part 5 Design by analysis. Protection against buckling clarification
2) that is not specifically addressed by the capacity reduction factor.
In my opinion, this is one of the biggest issues with the elastic/eigenvalue buckling analysis. Between that and the inherent issues with eigenvalue buckling, I only recommend using Option 3 - the elastic-plastic buckling analysis method.
RE: Section VIII, Div 2 Part 5 Design by analysis. Protection against buckling clarification
For Option 3. It says to explicitly consider the imperfections. Can you please give some insight into what exactly are these imperfections? Are they talking about manufacturing imperfections or imperfections induced by loads? I am planning to load up the model with the nozzle loads and perform a linear static analysis and then use this deformed model to perform the collapse analysis.
Thanks,
Jaspreet Hothi
RE: Section VIII, Div 2 Part 5 Design by analysis. Protection against buckling clarification