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RE: Construction/Isolation Joints for Composite Slab on Steel Beams

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This might seem trivial but I'm looking at the effect on the beams as much 
as anything. The analysis model I'm using (VA 10.0 with areas designated to 
 act as slab elements) is of course showing me the weird effect of the slab 
 bending over the girder in the "secondary" beams, and it's just bugging 

That put me in mind of what actually happens in the real-world structure.

I understand Harold's point but what Will is saying here also makes a lot 
of sense particularly in the application I have.

FWIW, this is an industrial equipment platform, and so will use 
normal-weight concrete (the equipment weights are such that the added load 
from using normal-weight concrete is relatively slight). I'm using a 6 inch 

-----Original Message-----
From: seaint-seaosc(--nospam--at) [mailto:seaint-seaosc(--nospam--at)] On 
Behalf Of Will Haynes Sent: Saturday, December 21, 2013 3:47 PM
To: seaint-seaosc(--nospam--at)
Subject: Re: [SEAINT-SEAOSC] Construction/Isolation Joints for Composite 
Slab on Steel Beams

For joints parallel to secondary members, ACI 302 has locating the 
construction joint in the middle of the slab between beams (middle 1/3rd is 
 probably sufficient) and close to a support where the joint crosses the 

When parallel to a girder, it has to locate the joint off of the girder 
enough to develop the girder slab flange in bending, which it states that 
about 4'-0" is usually enough for this. The joint should be on the side of 
the girder that will split the pour up so that the girder flange will be 
part of the second pour allowing the secondary beam to deflect in the 
initial pour and the girder to deflect completely before the second pour 

I don't know your slab thickness but a dowel basket plus lapping the WWF 
through the joint should work, added rebar fully developed on either side 
of the joint I think would work better if shear is a concern.

Will Haynes

On Sat, Dec 21, 2013 at 1:42 PM, Polhemus, William

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