I'm attempting to design attachment of cold-formed metal track to the top of concrete over metal deck using X-U PAFs. The substrate in this project is 2-1/2" NW Concrete over 1-1/2" 20ga composite metal deck (4" total thickness of system).
I've found information that requires concrete thickness to be minimum 3x the embed depth of the PAF used. Does that requirement apply to concrete over metal deck? If so, does that requirement consider the total system thickness, or only the thickness of concrete above top of metal deck?
Hi Mike,
Published data for the X-U into concrete is based on testing into a concrete slab, but the minimum concrete requirement would apply since fastening is occurring on the concrete side of the deck. Engineers may conservatively treat concrete over metal deck as a slab if there is sufficient thickness above the upper flute, but it will ultimately fall to engineering judgement on how to evaluate this condition. Technical data for the X-U may be found on page 36 of Hilti's Direct Fastening Technical Guide or ESR-2269.
Regards,
Matthew