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RE: composite and non-composite steel beams-curved in plan

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     When I had to use curved beams to support concrete to get circular 
parameters it has always been my position that the top and bottom flanges must 
be supported. I use a small angle brace from the bottom flange to the deck at 
about the third points. The torsion caused by  the difference between the cord 
of the circle and a straight line between supports is analyzed for torsion and 
the warping stress treated like weak axis bending stress.
    The best option is to keep the beams straight and cantilever the deck.

-----Original Message-----
From:	Sandip Guha [SMTP:sandip.guha(--nospam--at)]
Sent:	Wednesday, March 15, 2000 11:07 AM
To:	seaint(--nospam--at)
Subject:	composite and non-composite steel beams-curved in plan

Dear Sir,

I am in the process of designing a roof and a floor framing system with
steel beams/girders that form the perimeter of a circle of diameter 106 ft.
Four columns, spaced evenly along the circle, supports the metal roof deck
and the composite floor slabs (4-1/4" lightweight concrete over a 1-1/2"
metal formdeck- total thickness is 5-3/4"). My questions are:

	1) 	In roof diaphragm, can the metal deck be considered to
resist the torsional stresses resulting from the steel 		beams that
are curved in plan (radius of curvature 53 ft., arc length 83 ft.,
eccentricity of curved girder is 		6.74 ft at center of beam
and nil at supports (48" dia concrete columns).

	2)	In floor diaphragm, can the composite floor be considered to
be able to resist the torsional stresses resulting 		from curved
steel beams/girders?

	Thank you for your prompt attention. Sincerely,