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Re: Bending Anchor Bolts

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Title: RE: Bending Anchor Bolts
These types of repairs are not uncommon. The repair process itself must be performed methodically by a skilled craftsman, or else plan to replace or modify these anchors. 
 
Keeping the heat below the lower transformation temperature (approx. 1333F), Heat the area to be repaired uniformly to 1200F maximum and verify by temperature indicating crayon or a calibrated pyrometer.
The bending motion must be a controlled, smooth action. Bending to quickly will put a "kink" in the anchor. This includes placing a nut and hammering the end of the anchor to return it to it's home position.
Placing a pipe over the damaged anchor while it is hot and progressively bending back to it's original position will solve your problem.
Do not accelerate cooling or quench with water, allow to cool to ambient temperature.
 
I would also recommend pull testing a small percentage of the damaged anchors to verify the integrity of these (pick the ones with the greatest damage). This is to confirm if any real damage was done when the original force to bend them was applied.  
 
Daniel G. Luna
SCWI
----- Original Message -----
From: John Pluta
Sent: Monday, December 03, 2001 9:09 AM
Subject: Re: Bending Anchor Bolts

Please send the articles to me.
 
John Pluta
MSI General
P.O. Box 7
Oconomowoc, WI 53066
----- Original Message -----
Sent: Thursday, September 27, 2001 7:06 AM
Subject: RE: Bending Anchor Bolts

>I've got a project where the A36 anchor "rods",
>if they weren't placed in the wrong spot,
>they've been driven over and bent down at
>angles up to 60 degrees. Fortunately the
>braced bays were anchored with heavy dywidag
>tempcore rods and don't seem to be damaged.

>I'd like to give the contractor a repair spec
>which involves pre heating before bending the
>bolts back to plumb. Does anyone have any idea
>how much pre heat I should require? I guess this
>means what shade of red should the
>bolts be heated to? Or is "red" too much?

The Research Council on Structural Connections is in the process of preparing a specification for design and construction of anchor rods, much like the one they currently have for high-strength bolted joints. It has some coverage of remediation and repair, including for the cases you're dealing with. It is not final, but I'm sure you could get some input from Professor Robert Dexter at University of Minnesota, who is leading the development of that spec. He's a good practical guy.

His phone number is 612/624-0063.

Charlie