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crane / curved beam

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David,

You mentioned “built-in stresses.”  I assume you mean stresses due to cold-bending the beam.  As long as they don’t buckle or tear a flange doing it, I think you can ignore those stresses.  The beam had near-yield residual stresses before the fabricator took it off the truck; it still does after they bend it.  We routinely ask fabricators to camber beams, which they do by bending them past yield to hold the bend.  We take no deduction in strength for these beams.

 

I agree with the other posters:  weld a box (HSS) section to the top flange.  Even if your narrow little W8 can make stresses, the torsional deflection will probably kill you.

 

On another topic, check with your crane supplier to make sure the trolley can negotiate a 4 foot radius.  That’s about the point they usually start to bind.  I’ve been told by one supplier to keep to a 6 foot radius or greater.

 

HTH,

 

Mike Hemstad

TKDA

Saint Paul, Minnesota.