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RE: Steel - Beam with bent compression flange

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Michael D Zaitz wrote:

We have a frame for dumping of trucks for a client wher the compression 
flange the beam is bent approximately 1/2".  This is a multispan 
condition, and the deformation occurs on the bottom flange of the beam 
about 4" from the support which would be a brace point.  Under my worst 
loading the cross section would have a bending stress of 6.51 ksi.  An 
inflection point occurs 8 ft away and from then on the beam is contimuous 
ly braced.  How would you check the beam for the deformed area.  One idea 
(which I think is conservative) is to take the piece of the flange that 
is bent and treat it as a column with a 1/2" eccentricity.  Note the 
flange is bent on each side of the web (if anyone has seen wide flange 
columns hit by forklifts where the flange twists they would have a good 
picture of what this looks like).

Anyone have other ideas on how to check this?




Typically I would add a stiffener or stiffeners at the bent flange locations 
in order to resist the inward or outward component of the compressive force 
since it is no longer linear (draw a free body diagram if needed).  I would 
then check the stress at the bent section do the changed section modulus but 
in your case the stresses seem pretty low.

Good Luck!!

Lanny Flynn