instability problem in rectangular steel tank design

[EnricoCorvaglia]

Hello to all
Do any of you have expirience about design of an open rectangular steel tank?
I modeled a rectangular tank and designed according to Eurocode 3 and the aisc, in both cases I have a problem of instability as outlined in the attached figure.
I tried to reinforce and use different shapes (even closed shapes) but the problem persists.
Can someone help you solve it?

thank you

italo

[EnricoCorvaglia]

Hello to all
Do any of you have expirience about design of an open rectangular steel tank?
I modeled a rectangular tank and designed according to Eurocode 3 and the aisc, in both cases I have a problem of instability as outlined in the attached figure.
I tried to reinforce and use different shapes (even closed shapes) but the problem persists.
Can someone help you solve it?

thank you

Italo

[Artur.Kosakowski · Accepted solution]

Hi @EnricoCorvaglia

If the steel profiles are welded to the tank plates shall their unrestrained buckling length be 7.5 m?

If I managed to answer your question(s) press the Accept as Solution button please. This will help other users to find solution(s) much faster. Thank you.