Shear buckling of a deep unstiffened plate
Shear buckling of a deep unstiffened plate
(OP)
Friends
I am analysing a steel silo made of roof, barrel, bottom hopper and columns and braces. The roof, barrel, and bottom hopper are all unstiffened plates. See attached diagram.
I have used thin shell elements and can get output contours of Nx Ny Nxy Princepal stress etc which will tell me the magnitude of membrane stresses in the plate. Obviously I will keep these values below the yield stress of the material. But I have been told that you get a problem of 'shear buckling' in the lower regions of the barrel near the column supports.
I am wondering how to check the section for shear buckling. The barrel is 160 inches tall, 120 inches dia. Supposing I know the magnitude of principal compression in the lower region, what cross-section area is to resist that?
Any of your thoughts will be appreciated.
Normm
I am analysing a steel silo made of roof, barrel, bottom hopper and columns and braces. The roof, barrel, and bottom hopper are all unstiffened plates. See attached diagram.
I have used thin shell elements and can get output contours of Nx Ny Nxy Princepal stress etc which will tell me the magnitude of membrane stresses in the plate. Obviously I will keep these values below the yield stress of the material. But I have been told that you get a problem of 'shear buckling' in the lower regions of the barrel near the column supports.
I am wondering how to check the section for shear buckling. The barrel is 160 inches tall, 120 inches dia. Supposing I know the magnitude of principal compression in the lower region, what cross-section area is to resist that?
Any of your thoughts will be appreciated.
Normm





RE: Shear buckling of a deep unstiffened plate
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Shear buckling of a deep unstiffened plate
RE: Shear buckling of a deep unstiffened plate
shear buckling is related to shear, not compression (maybe you're hung up on the word "buckling"). thin panels buckle in shear (try it with a sheet of paper), buckling along the diagonal direction ('cause the buckles carry the shear). in your case i suspect it'd involve a lateral load case (wind ?). look up diagonal tension. i'd've thought it was something that your code addressed, that you shouldn't need someone to say "check this" ...
RE: Shear buckling of a deep unstiffened plate
Your understanding is pretty much correct. For methods for buckling stress prediction try books by Bruhn, Niu, ESDU, or maybe HSBC for shear panel buckling allowables. It's a bit more trickey with curved panels than flat.
Reinforcement of the thin shell near the supports where the shear stresses peak will increase the buckling strength. This can be done using thickness doubler plates, or finger plates (series of tapered raised flanges radiating from the column/shell intersection).
gwolf
RE: Shear buckling of a deep unstiffened plate
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Shear buckling of a deep unstiffened plate
RE: Shear buckling of a deep unstiffened plate
At any case, a silo filled with "stuff" should not expect to have shear buckling (similar to a beam shear web).
Perhaps you should get additional information, and restate the problem.