Column buckling

[mohammad1367]

Hello friends,

i have a question about column buckling.

Assume a circular stiffened plate which is simply supported along its edge. a uniform lateral distributed pressure acts on the plate.

The stiffeners are welded to the top of the plate.(I have attached the picture). some detail information:

Diameter of circular plate =1000 mm

Pressure :15000 Pa

Thickness of plate = 6 mm

stiffener size : 50 mm * 10 mm

Which kind of buckling can happen for the stiffeners? any probability for column buckling?

Some one has asked me to check for column buckling but i believe the only probability for buckling is LTB (Lateral-torsional buckling)

I will appreciate any help.

 

[JAE]

The stiffeners might buckle with locally (local buckling of the upper free edge) or by a lateral buckling due to bending forces in the plates where a larger segment of the plate would lean sideways.

The lateral torsional buckling would be resisted by the connection of the stiffener to the circular plate I would think.

The local buckling would be avoided by having a thick enough stiffener plate.


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[BAretired]

This is similar to the problem in your thread507-399232. The load is greater and the stiffeners are placed on the opposite side of the circular plate.

As discussed before, it would be better to place the stiffeners on the unloaded side of the plate because the compression edge would then be laterally braced by the circular plate.

If stiffeners are to be welded on the loaded side, lateral torsional buckling could be checked by applying principles given in the code. As a suggestion, you could calculate the maximum compression C in each stiffener, then ensure that the circular plate is capable of resisting a moment equal to 5% of C.e where e is the eccentricity of the centroid of compression from the centerline of plate.

BA

 

[mohammad1367]

OK, Thanks to BAretired and JAE for your useful information.

from your explanation, i found that the probability of column buckling is zero.

for column buckling, axial load is necessary. am i true?

THX.

 

[KootK]

Column buckling is indeed generally a compression phenomenon. Your stiffeners will likely be in axial compression for the most part and your colleague may have suggested column buckling as an approximate means of checking the stiffener's capacity. If you still have acces to the colleague that made the recommendation, have them clarify it for you.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[mohammad1367]

Thank you KootK.

i talked to my colleague. i think he made a mistake. he is referring to standard API Bulletin 2V. he told me that one of the important parameter that affects buckling of stiffener is slenderness ratio. he concluded that since LTB (lateral-torsional buckling) and LB (Local Buckling) doesn't consider this important parameter, column buckling should be checked!...