Anchor Rods with single nut 1

[Samwise Gamgee]

The erector told me that the anchors with double nut have an embedment of 10" which is the same depth as that of the pedestal and there is no wiggle room for error. He suggested using a single nut and tack weld the nut to the rod. Is this allowable ?

The intent for me to call our double nut was that I wanted to avoid the turning of the anchor. (And these are braced framed foundations)

 

[HTURKAK]

The following snap is, copy and paste from PIP STE05121 Anchor Bolt Design Guide

...and typical anchor detail (FIGURE A ) , shows tack welded nut.

 

[KootK]

Wouldn't this cause any unwanted localized stresses due to the nut and anchor rod expanding at different rates?

1) Yes.

2) I suspect that you get the localized stresses even when the same material is used on both sides of the tack weld.

3) I've been tack welding dissimilar steel in these applications. The weld should be on the bottom of the nut which ought to reduce the impact of the weld relative to, say, welding on top of the nut where the bolt is in full tension.

4) The snip below is the advice that I got from Portland Bolt when I asked this same question a decade or more ago.

 

[phamENG]

Samwise - always a good idea to specify anchors made of weldable material. You never know when there's going to be an error or accident in the field (and with anchors most will tell you it's when, not if), and if they aren't weldable there aren't many ways to fix the problem. Ensuring that it's weldable (dual spec'd material as F1554 Gr. 36 and A36, F1554 Gr. 55 with welding supplement) doesn't add much to the cost from what most contractors have told me, and saves boatloads of money if you need to repair an issue later. (Weld on an extension vs. removing the entire footing to recast new anchors.)

 

[dik]

Make sure you spec S1 with the above... it's weldable. I only use Gr. 55 S1. Replacement for the Gr.36; it's almost the same price and a bunch stronger, for nearly free. I use it for replacing A307 anchor rods. Unless spec'd A307 doesn't have to be weldable, and Gr 55 is stronger.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik