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Re: Opinions Please: Composite Beam/Deck Slab

[Subject Prev][Subject Next][Thread Prev][Thread Next] How much of the concrete is being displaced? How thick is the slab?  If you have 3-1/4" lightweight over 3" or 2" metal deck, I would say move the conduits and hang them from the slab after the floor is poured. If the conduit if aluminum, then I don't think you want conduit in the topping slab.

If the conduit is running parallel to the beam, you can check the revised composite beam section (reduced flange width to not include the concrete zone with conduit.) and see if the beam still works, probably have to add more studs, and have a smaller maximum moment capacity. Hopefully the conduit is more than 12" away from the centerline of the steel beam, where you could treat the beam as a perimeter beam with composite on one side only for design purposes.

If the conduit are running perpendicular to the beam, I would probably have them move the conduits, especially if the conduit crosses at midspan of the beam and the topping slab thickness is thin. You have lost the compressive strength of the concrete in the composite beam cross section due to the void the conduit creates.

Michael Cochran S.E.

In a message dated 2/28/2002 10:53:01 AM Pacific Standard Time, kefix(--nospam--at) writes:

Conduit has been laid on the deck.  Concrete has not yet been placed, but is
scheduled to be placed tomorrow.  Are there conditions in which conduit cast
horizontally in the plane of the slab is acceptable?

-Keith Fix, PE