Plate in Compression

[bigmig]

I'm looking for some tips in designing a piece of 5" wide, 1" thick x 20" tall plate loaded in concentric axial compression.
I've looked through the AISC Section B4 and I'm just not seeing my plate in the width to thickness ratios.

The plate is just a free standing plate with a single bolt top and bottom, so the end conditions are "pinned".
I found this formula online (see image below), but am having trouble making sense of the discussion. What am I missing?

 

[KootK]

At the proportions that you're dealing with, this is probably a simpler problem than you're envisioning. I'd just call this thing a pin ended column and design it as such, forgoing any b/t checking.

 

[sbisteel]

I'd be inclined to look at case 3, "all other unstiffened elements".

 

[271828]

This isn't a "plate buckling" problem, as the term is used in AISC. Section B4 applies to local buckling of individual elements of a section, not to an entire section itself.

This is a small column with rectangular cross-section. Compute the strength per Section J4.4.

 

[JStephen]

The buckling equation you reference is likely for a rectangular plate with supports along the edges, but it would just be a little column as noted above.
If bending is significant, there is also a section in the newer AISC code for bending of flat bars that would apply to your case.

 

[rb1957]

Do you guys use "effective width" of a plate in compression. For Aluminium it works out to be 30t, Steel could be different (I remember it depends on E)

one bolt top and bottom ... a column 30t wide.

Mind you, there are a tonne of issues we're not addressing ... flexibility of the panel, vibrations, to "non-standard" attachment (for a panel), ...

another day in paradise, or is paradise one day closer ?

 

[bigmig]

Thanks all. Very great input......Love Engtips!!!!

 

[271828]

rb1957 "Do you guys use 'effective width' of a plate in compression."

We use an effective width approach to account for local buckling and post-buckling strength of plate elements within a cross-section. It's in Section E7 of the AISC Specification and it's similar to what's done for cold-formed steel, but simpler.

I bet this is more what you're typing about: When a gusset connection plate is wide in the direction transverse to the load, we use the Whitmore Section concept in which a region in the vicinity of the bolts or welds is considered effective.