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Re: Composite Floor conventions

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Thanks for the replies - it confirmed what I thought I knew. The 12" was probably just a reference by the "professor" (actually a working SE who taught one or two classes in the grad program) and his personal rule of thumb. I'm still not sure if it was a max (to avoid having to puddle weld the deck in addition to studding it) or a min, but it sounds like it really doesn't matter.

I read through the 2005 spec., and didn't see the 25% limit, which is why I asked. I don't have an ASD book anymore, or I would have checked. Somehow I missed the 6xslab thickness in I3.2d(6).

RAM confirmed that the # studs = total end to end, that you can set the limit for composite action below which the beam will be designed as non-composite, and that the newer versions of the program now optimize studs as pairs on uniformly loaded spans (it just looks wrong to see a uniform span with an odd number of studs). A big thanks to Seth in tech support at RAM (Bentley) for answering my questions very quickly, especially since I don't own the program.

Stay tuned for a followup question...


Carter, Charlie wrote:

The number of studs on the drawings *should* be the total number
distributed over the segment, as the person who has to build it likely
does not know we calculate half the number. I'd get verification of that
from RAM, too, though.

There is a good discussion about lower percentage composite action on
page 16.1-311 in the 2005 Specification. There is no codified limit, so
you can use your engineering judgment.

Maximum spacing of studs is given in Section I3.2d(6) on page 16.1-88 as
6 times the total slab thickness or 36 in. Maximum spacing of deck
attachment (studs or puddle welds) to the beams is 18 in. per Section

Not sure where the 12" rule is from.


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