lateral-torsional buckling and local buckling

[mohammad1367]

Hello every body

Does anyone know how to design laterally loaded stiffened panel?

Design considerations are lateral-torsional buckling and also local buckling.

i am completely confused!....

 

[BAretired]

Provide a sketch. What kind of panel? How is it loaded?

BA

 

[mohammad1367]

Thanks for your reply.

a circular plate with thichness of 5mm which is loaded by uniform lateral pressure of 5935 Pa.

2 plate stiffener with rectangular cross section (100mm * 10 mm) are welded to the plate inorder to prevent large deflection.

I have attached the picture.

Material :Steel

 

[BAretired]

I am assuming that the 100mm dimension of the stiffener is normal to the plate although your drawing does not specifically say so. It is not clear from your drawing whether the stiffeners are on the loaded or unloaded side of the plate. If they are on the unloaded side, lateral torsional buckling (LTB) is not an issue because the compression edge of the stiffener is laterally braced by the plate. If they are on the loaded side of the plate, lateral torsional buckling is something which could be checked but the stresses are so low that it seems unlikely there would be a buckling problem.

BA

 

[mohammad1367]

Thanks for your reply sir,

I have attached the picture for you.

Ok, there is no probability for LTB.

How can I check local buckling?

I also need to know about "AISC code unity check".

i am mechanical engineer. would you please tell me how to check unity? i know nothing about it.

Best Regard.

 

[BAretired]

BA red[/color]]I have attached the picture for you.
Nice picture.

Ok, there is no probability for LTB.
That is correct.

How can I check local buckling?
Local buckling of what? I don't see any possibility of local buckling.

I also need to know about "AISC code unity check".
i am mechanical engineer. would you please tell me how to check unity? i know nothing about it.
I'm from Canada, so I don't use AISC and am not familiar with their unity check. Perhaps someone else can respond to that.

BA

 

[vhengr]

Md.

"How can I check local buckling?"
-----------------------
Since plate is not subjected to any kind of point load or non-uniform loading; I don't see any local buckling problem in a plate. It seems that you are interested to know the deflection of the plate under uniform pressure loading.

Refer "Roarks formulas for stress & strain" book to determine the centre deflection, the max. stress of circular plate with uniform pressure loading.

This type of plate and loading are covered in table 11.2 case 10a.

else go for FEM model of plate and analysis to decide extra stiffening requirement of the plate.

Cheers! -VH

 

[mohammad1367]

Thanks.

Fortunately, it seems there is no probability of buckling.

I will be appreciated if anyone help me for "AISC unity check".

 

[Agent666]

I think you are referring to local buckling in that only the portion of the plate either side of the stiffeners is really effective, and beyond this the plates can buckle and are not effective. It's similar in concept to a wide thin plate flange on a beam. You don't use the full flange when working out the ultimate caoacity, but rather some portion of the outstand based on how slender the plate actually is.

Look into the plate slenderness limits (b/t ratios) in AISC to determine how much plate is effective in resisting the load. AISC isn't my code either so don't know where this is in the standard specification

 

[BAretired]

Why are the stiffeners so large? With 100 x 10 stiffeners, even without tee beam action, the stiffeners appear to be excessive. Have you done any calculations on the stiffeners and if so, what have you found? What is the maximum fiber stress in the stiffeners?

BA

 

[mohammad1367]

I change the stiffener dimension to 50 mm * 10 mm

maximum stress in Stifener : 14.68 Mpa

maximum stress in plate : 3.33 Mpa

the deflection of plate should not exceed 2 mm.

Maximum deflection is 0.22 mm.

So, the problem is solved!

Thank to every body.