Tilt Wall Reinforcing for a Knockout Panel

[alumpkin]

Looking for your opinion concerning the need to reinforce tilt wall knock out panels. I've seen engineers both provide and leave out reinforcing at the knock out panel.

For a typical 10'-0" x 10'-0" opening I would leave out the reinforcing in the knock out portion. The jambs have been designed for the wind load. The C&C wind load is 17 psf (ASD). So, wl^2/8 (conservative) = 30,600 in-#. section modulus is bd^2/6 and for an 8" panel ….S=128 in^3. For 5000 psi concrete …..cracking stress per SEAOC is 5*(sqrt 5000) = 354 psi.....that a safety factor of approximately 1.5....for a conservative moment.

So, I would tend towards no reinforcing required in the knock out panel.

Any thoughts or comments?





















Alan L. Lumpkin, MS, PE
Greenville, SC

 

[WARose]

To me, it would depend on how long we are talking that the panel could be in place. If it could be there for the long haul, I'd reinforce it. (Especially in a high seismic region.)

 

[alumpkin]

WARose,

Thanks for the response. Not in high seismic region nor high wind. Panel could be there for several years before the expansion begins.

Alan L. Lumpkin, MS, PE
Greenville, SC

 

[WARose]

If we are talking years, I'd reinforce it. There are (probably) temperature considerations as well.

Saw cutting it (when the time comes) won't be that big of a deal.