25% composite action

[othiessen]

I remember reading somewhere that composite beams require at least 25% composite action in order to qualify as composite.

Is this listed in any code specification, and if so, could someone please direct me to it?

Thanks

 

[WillisV]

It is not actually a code requirement, but 25% is the typically accepted minimum for a number of reasons. See the Commentary to I3 the 2005 Spec (13th Ed. Manual) - p16.1-311 item 3.