Penetrations in Hollow Core Planks

[jborkowski]

I'm working on a condominium where a client wants to install an accessible shower in their existing bathroom. To do so, the contractor will need to install a 2" drain through the 12'X4' 12" hollow core plank the unit is built on. I have some details for the plank, but I don't have the size or tensioning of the reinforcing strands. As long as no reinforcement is cut, can a penetration that size be considered negligible? Does anyone know a way to show that the penetration is safe with the information available?

 

[dik]

You need to locate the strand... either from detail of the HC slab or by covermeter... preferably the latter.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[WesternJeb]

Second Dik's comment. Get some kind of NDT to confirm strand locations, it would likely cost $1,000 or so around here for that.

 

[jayrod12]

To directly answer your question, if no strands are cut, I see no issue with a 2" pipe (3" core) being performed on the plank.

 

[GeorgeTheCivilEngineer]

Would usually expect the hollow core to be backfilled/ grouted around penetrations. Although it's small I think I'd still spec that.

 

[JAE]

If the hole is near the end support, and it creates a 3" diameter vertical gap right through the "web" of the plank, that would definitely reduce the shear capacity a bit.
And most strands are located in line with the webs so - YES - get the strands located.

 

[jborkowski]

Thanks for the good advice everyone, we're getting the plank scanned and the strands located. I also got some guidance from the plank manufacturer for anyone who's curious, penetrations are acceptable as long as they're limited to the hollow core section of the plank and no strands are cut. No more than 1/3 the width of the plank can be cored for penetrations in that manner.