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RE: Anchor Bolt Splice

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>I've got some critical anchor bolts that
>have been set short in the field.
>They are 1 1/4" dia. A449 in tension
>only.  I'm searching for a fix.  Here
>are my questions:
>1.  How much thread should be showing
>above the nut to achieve full design

A flush installation (zero threads showing above the nut) will develop the
strength of the rod.

>2.  Is there a documented relationship
>between the number (or length) of
>threads actually engaged and the design
>strength of the bolt/nut interface?
>(i.e. a reduction curve when the bolt
>is shorter than required)

I believe the Industrial Fasteners Institute publication Fastener Standards
has such a formula. They're at

>3.  I'm thinking I'll have to weld an
>extension to the existing bolt.

A449 is heat treated to get the higher strength. Welding will likely undo
that heat treatment and corresponding strength. I would not recommend it.

>Is there a prequalified full pen weld for two equal diameter rods?
>4.  Will I need to preheat the base material?
>5.  Will I need to specify special electrodes for the operation?

Perhaps you can use a threaded coupling to attach a threaded extension.

Hope this helps.


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