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Re: camber for two way slabs

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David,

There is no required or recommended amount of precamber.

You have to keep the deflections within the code limits for visual effect or ponding plus protection of attachments if they may be damaged by deflection.

Precamber can be used to reduce visual deflection. You precamber by the amount you want to reduce deflection by to improve performance visually or for ponding but obviously not by so much that you cause upward deflection problems. Normally I would precamber by the self weight deflections or a little more (not long term value).

It is an engineering judgement decision.

If you are using ACI code methods for calculating and accepting deflections for flat slabs you could be out by a factor of 2 or more for flat slabs anyway (un-conservatively) so I am not sure if precamber will really help that much.



At 07:02 AM 3/12/2004, you wrote:
Just trying a second time with this one...
 
Does anybody have any references for the required / recommended camber for a two way slab. I have seen it done on drawings and I assume that it is calculated with a (DL + 20%LL+/-) value and then multiplied by the estimated long term factors given in the code...or a similar approach. I have looked through all of my references and I can't see any sign of it??
 
thanks
Dave

Regards  Gil Brock
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