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Re: ROCK ANCHOR PROOF TESTING

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Freilinger, Shawn W wrote:
> 
>                 I am design a rock anchor foundation for a
> telecommunications tower.  Is anyone familiar with proof testing of these
> rods?  The anchors are about 11' deep into solid bedrock.
> 
>                 My company has required a couple different ways of proof
> testing these in the past.  One method is to grout the bottom 1/3 of the
> hole and then pull with a third of the expected anchor tension.  The other
> method is to grout the entire bar and then proof test it for combined
> stresses (bending and tension).
> 
>                 If anyone has some "standard practice" knowledge or reading
> resources, I would appreciate it.
> 
>                 Thanks,
>                 Shawn
> 
>                 Shawn Wicks Freilinger
>                 Valmont/Microflect
>                 Shawn(--nospam--at)valmont.com <mailto:Shawn(--nospam--at)valmont.com>
>                 (503) 315-4515
> 

Our practice has been to grout the full bond length. Load it to 133% of
the design load. Compare the measured elongation with the theoretical
elongation. Hold the load for 30 minutes and check for signs of unusual
creep or failure. Reduce the load to 100% of the design load and lock
in. It is considered good practice by many practitioners to have a
minimum bond length of 15 feet.

Bruno Côté
BOCTE(--nospam--at)ibm.net