Coring holes in Double Tee top flange 1

[casperzz]

I've been looking for a guide on coring holes for mechanical ducts in precast double tee top flange, any recommendations on where to get that? I'm not finding anything on PCI website.

 

[Ingenuity]

What size holes you thinking about?

 

[casperzz]

Up to 34". Center line distance btwn. flanges is 40". So pretty much takes the whole flange btwn. webs.

 

[KootK]

I would expect that to exceed any "guidelines" per se. I'd think that you'd have to check your flexure based on the reduced flange width available and do a little strut and tie to deal with reinforcing for the flow of forces around the opening. Whether or not it's a big deal surely depends where on the span you land.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[dik]

Likely too big... can you contact the precast supplier? Almost no flange left between the stems...

Dik

 

[JAE]

If it is toward the ends of the member, the moment and the corresponding flange stress due to flexure will be smaller and thus the flanges may not be as critical.

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[racookpe1978]

So the sheetmetal (HVAC ducts) is going to destroy the stressed load-bearing concrete flanges holding up the entire building? You're solving the wrong problem!

Yes, it will require the sheetmetal (actually, the flow calc's for the sheetmetal) to be analyzed instead of just picking out tubes from the book, but allow a row of 12" x 24" rectangular holes to be notched in the concrete at the joints between two adjacent flanged pre-cast members - 6 inch U-shaped notches in each of two paired beams. The sheetmetal - and, yes, I am insulting the sheetmetal ducts - is rebuilt to accommodate the plenum, plenum-to-rect, rectangular sections, and then the receiving plenums to allow the ducts to continue below the floor.