Tilt-wall reveals

[CTSeng]

Getting mixed opinions on how to design a tilt-up concrete wall that has architectural reveals. My approach has been to ignore reveals when not in the middle 1/3 of the height and when in middle 1/3 use the reduced section except for the deflection calculation.

How do others design for reveals.

 

[JedClampett]

I center the reinforcing in the reveal section and use that section for my design. It makes a minor difference in the design and I sleep better at night.

 

[rgerk]

Conservatively, I always use the reveal section and design for rupture of 5*sqrt(f'c). If I can't make that work I would do a redesign with the steel in the center of the overall thickness and check the actual moments and shears at the reveal locations. They aren't always located at the max shear and moment.

 

[haynewp]

We used to conservatively count the reveal depth even when they were not at the idealized max moment location. This way we were pretty much covered if there was partial fixity at the base or top of the panel that skewed the moment diagram. Normally it was only about 3/4" for reveals anyway.


{Looks around...takes another swig of beer}

 

[swmiami]

Does "ignore the reveal" mean that rebars have less coverage at the reveal (if both faces are reinforced)? Will corrosion be a concern?

 

[Lutfi]

swmiami,

I always require minimum cover over rebars at the reveals. ACI requires the cover for corrosion purposes.


Regards,
Lutfi

 

[UcfSE]

I do the same as Jed. I use the section thickness at the reveal for all my numbers except self-weight, which uses the full thickness. Up to this point I haven't had access to a finite element program or I might do it a little different.

 

[CTSeng]

Thanks for the input.
I agree, use the thickness at the reveal except for self-weight.

However, when only minimum steel (vertical or horizontal) is required then what thickness do you use?

 

[swmiami]

Full thickness should be used to calculate reinforcement for temperature and shrinkage. It becomes clear if you treat the reveal as a crack.

 

[CTSeng]

What do you use for minimum concrete cover requirements?

ACI permits use of precast covers for site precast but I've seen some site tilt-up that is not near the quality observed in a precast plant.

I've used 1" minimum as a middle ground where needed.

 

[swmiami]

Section 2.15.2 of ACI 551R-92 (Tilt-Up Concrete Structures) allows any cover dimensions between the required minimum for precast and cast-in-place concrete. I would use 1" for exterior and 3/4" for interior (not exposed to earth or moisture change).

By the way, is there a set tolerance requirements or any standard corresponding to "manufactured under plant control conditions"?

 

[swmiami]

If the rebars at the reveal locations are epoxy-coated, I think the concrete cover can be reduced. Any commnets?