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Re: DESIGN / ANALYSIS TREATMENT OF "HAIRPIN CONNECTIONS"

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Jim Kestner wrote:
> 
> Occasionly we get involved in foundations for metal buildings. I use
> hairpin connections at the piers to transfer the column thrust into
> the floor slab reinforcing if the thrust is of a low magnitude. For
> higher magnitude thrusts,  I recommend tying between opposite columns
> with rods, rebar or angle cast in the floor slab.
> 
> For the hairpin method, I use the friction between the slab and the
> subgrade to transfer the forces out of the slab into the ground. There
> are a number of things to be aware
> of with this method:
>     1. do not use an unreinforced slab...use WWF or rebar in the slab
>     2. make sure sawcuts do not cut the reinforcing at the joints if
> you are counting on a
>     force  transfer to an adjacent slab
>     3. a  vapor barrier will reduce the coefficient of friction and
> will make this
>     method impractical
>     4. do not count on friction in the failure zone of the backfill
> (similar to locating
>     an anchor wall outside the failure zone for sheet piling)
>     5. Extend the haipin far enough to engage as much rebar as
> necessary to
>     safely transfer the forces.
> 
> Jim Kestner, P.E.
> Green Bay, Wi
> 
> 
> Robert Rogers wrote:
> 
>       I HAVE SEEN (ON SEVERAL DRAWINGS) THE USE OF BENT
>      REINFORCING STEEL
>       (USUALLY BENT AT 135 DEGREES) WHICH IS PLACED IN THE TOP OF
>      A CONCRETE
>       PIER (JUST BELOW THE COLUMN BASE PLATE AND AROUND THE
>      BACKSIDE OF THE
>       ANCHOR BOLTS) AND TIES THE PIER TOP INTO THE CONCRETE SLAB
>      ON GRADE.  THIS
>       IS A TYPICAL DETAIL FOR PRE-ENGINEERED METAL BUILDING WHERE
>      THE LATERAL
>       THRUST LOAD IS TRANSMITTED INTO THE SLAB-ON-GRADE SUCH THAT
>      IT HELPS
>       RESIST ANY LATERAL FORCES.  IF ANYONE KNOWS OF A GOOD
>      DESIGN/ANALYSIS
>       REFERENCE FOR THIS CONNECTION PLEASE LET ME KNOW.  (I'M
>      ASSUMING ITS JUST
>       A MATTER OF DEVELOPING SUFFICIENT TENSILE STRENGTH IN THE
>      REBAR TO
>       TRANSMIT THE THRUST LOAD).
> 
> 
> 
R.R.

Think your caps look great !!

Can you send the in bold also !!

Donn Wooldridge RA/SE
Phoenix, AZ