Tilt-up hooked dowels

[WAstruc10]

For tilt-up wall panels (especially 5.5" ones), how would you typically provide hooked dowels to the slab pour strip (or to a concrete mezzanine floor if needs be), since the hook development length is too long? It seems like a commonly overlooked error - even the TCA engineering manual shows it this way. Epoxy dowel development lengths are shorter but the contractor won't be happy about all that drilling. Thanks for your thoughts on this.

 

[DarthSoilsGuy]

never designed one. on welding inspections and rebar inspections i've seen

the majority of the slab is poured to give a surface to cast the panels on. a ~4 strip along the edge where the slab isn't cast along the perimeter. 90 degree hooks are cast in the wall with the development length hanging out in the air perpendicular to wall. the exposed rebar is cast into the additional floor strip of concrete after the roof-steel is done. it's been a while since i've seen one, i'm sure someone else will have better design answers. I think i recall seeing one project have walls cast with mechanical splice ends to screw into.

-dsg

 

[csd72]

The hook doesnt need to be vertical, it can be horizontal.

csd

 

[sdz]

Hook or cog? Hook has 180 deg bend, cog has 90 deg bend.

 

[civilperson]

Hooks can be either 90 or 180 degrees. Full development strength can be obtained with mechanical or welded cross members to the rebar in question.

 

[UcfSE]

I think all you can do is note that you cannot develop those bars. As you noted, you can't get the minimum development of 6 inches in a 5.5-inch wall.

I think it gets boiled down to engineering judgment in the end. An allowable stress approach may provide a rational method since, if you cannot develop the yield strength, it doesn't make much sense to use an ultimate- or limit-state approach to the strength of the dowels we're discussing.

 

[csd72]

Does ACI allow you to use cross bars inside the hook to help develop the stress. I know that some other codes do.

csd

 

[civilperson]

Welded cross bars of equal diameter can develop the rebars per ACI 318-05 Ref. 12.1.