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RE: Connection at the base of Tilt-up panels

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Joseph,

This can be handled in a few ways.

1) Treat the dowels as bolts and use bolt values for the shear transfer.
(High shear == mucho bolts!) This is fine for typical low shear panels.
2) Angle the bars so that a full development length can be achieved. We do
this alot with high force shear walls. The minimum hook development is 6".
The bar can be angled so that a 1.5 or 2" cover can be achieved and the
allowable ultimate load reduced to account for an ldh less than that
required for the fully accting bar by reversing the effect of UBC
1912.5.3.4. You also need bars coming out of the panel in both directions.
3) As an adjunct to this consider that two planes exist. One with steel
crossing a vertical plane and a horizontal plane between the panel and the
foundation. The code states that friction can be used to reduce the steel
requirement and does not specify a minimum amount of steel crossing the
plane. Accounting for vertical acceleration (if you are in a seismic zone)
reduces the friction a bit. For typical panels that have low shears much of
the shear is accounted for in the friction.
4) SOme use embeds and welded connections.

> -----Original Message-----
> From: From the desk of Joe Otto [mailto:jmo_engineering(--nospam--at)email.msn.com]
> Sent: Thursday, March 04, 1999 2:13 PM
> To: seaint(--nospam--at)seaint.org
> Subject: Connection at the base of Tilt-up panels
>
>
>
> I'm working on a single story concrete tilt-up building.  It
> is desired to
> use hooked dowels at the base of the wall to transfer the shear to the
> closure/footing/slab by means of shear friction.  The typical
> concrete walls
> are 6" thick.
>
> My understanding is, if you want to use shear friction, the
> dowels must be
> embedded at least their minimum embedment length or a have "mechanical
> anchorage".  Is adding an additional horizontal bar at the
> outside of the
> wall and hooking the dowel around it sufficient to provide "mechanical
> anchorage"?  Is it permissible to reduce the allowable shear
> friction based
> upon the embedment of the dowel?  How do you handle this situation?
>
> Joseph M. Otto, P.E.
> Fremont, CA
>
>
>
>
>