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RE: precomposite deflection limits

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Title: RE: precomposite deflection limits

>Does anyone know of any clearly documented, recommended or required
>(unlikely) guidelines to limiting the precomposite deflection of steel
>beams in composite floor systems? I've always tried to limit the total
>deflection to a reasonable number (1" or so, depending on the span) and
>the initial deflection was never a serious issue.

This is addressed in AISC Design Guide No. 5 "Low and Medium Rise Steel Buildings" by the late Horatio Allison and in AISC Design Guide No. 3 "Serviceability Considerations for Low-Rise Buildings" by Jim Fisher and Mike West.

In these references, two issues are addressed:

1. The effects on partitions and wall as in how much floor deflection can be tolerated. But if you are looking at beam deflection under wet weight of concrete, this may not be as big a concern since the partitions and walls most likely will be coming later. Said another way, post-composite deflections may be more relevant to partition and wall considerations.

2. The effects of concrete ponding. That is, the more deflection you get, the more concrete you get, the more deflection you get, and so on. In addition to this design guide, there is also an article in the 3rd Quarter 1986 AISC Engineering Journal by John Ruddy called "Ponding of Concrete Deck Floors" that will help you with this issue.

Charlie