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RE: Column Stiffeners

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> Carter wrote:
> I don't know why you would need a stiffener at a seated shear
> connection to a column flange. The vertical reaction is simply
> delivered to the column through its flange.
> Nacionales wrote:
The beam seat are just for erection purposes as per drawings.
The connection is a moment resisting connection, the flanges 
> of the column are welded to the flanges of the steel beam,so 
> the top and bottom flanges of the steel beam will have tensile 
> and compressive forces acting on the column flange. This is 
> how I understand, why the AISC code requires it. 
OK. Now I understand.
Stiffeners and/or doublers may be required based upon the provisions given in LRFD Specification Section K1 and/or related information in the AISC Seismic Provisions. Often, it can be shown that the flanges and/or web have adequate strength and stiffness without such stiffening (more so in wind and low-seismic applications, but there have been a few test programs that demonstrate the same for high-seismic applications). For a more detailed discussion of this, take a look at AISC Design Guide No. 13 Wide-Flange Column Stiffening at Moment Connections: Wind and Seismic Applications:
Although that erection seat may add some stiffness, I would not rely upon it as contributing anything to the strength or stiffness to resist the concentrated forces from the flanges without significant engineering investigation of the extent to which it could contribute. Most erection seats will add essentially nothing.