Anchor bolts with "not full" thread engagment 4

[Maturin]

Can anyone see any issues with calculating the thread capacity of a anchor bolt nut that is not fully engaged and comparing it to the applied load to determine if it is acceptable?

The anchors are 1" diameter Red Head anchors and are oversized for the loads they will see (approximately a 3:1 ratio of allowable concrete breakout capacity to applied load). The engagement is a little above one half the nut and the thread capacity is higher than the conrete breakout. Installing a coupler is not possible and I doubt that the bolt material is conducive to welding.

 

[desertfox]

I'm not a structural engineer but I assume not having full thread engagement might have an impact on fatigue.
desertfox

 

[chicopee]

If only under shear loading, you may be OK. But with tensile (cycling or noncycling)loads, I would not take a guess even with oversized anchor rods. Theoretically, you may be OK but I would not take a chance.

 

[connectegr]

I don't know if it matters, but improper installation will void any warranty regarding service strength. I would recommend core drilling and replacing the anchor. this may be a symptom of another problem. If anchor is too short an the surface, was adequate embedment provided at other locations? Where the anchors long enough? i rarely see cases were erector over drills holes.

http://www.FerrellEngineering.com

 

[dik]

chicopee... often shear resistance is developed by the tension capacity.

Dik

 

[fegenbush]

AISC Has a wonderful lecture available online regarding common field fixes. It is available here:

http://www.aisc.org/content.aspx?id=2168

On page 14 of the downloadable slides package, it details how to correct the anchor bolt too short condition.

I recommend checking it out and the solutions it recommends.

 

[Maturin]

Thanks for all the responses.

Fegenbush, the link you provided to AISC recommended field fixes is very useful and it does suggest analysing the nut engagement as an option to dealing with short anchors. Thanks.

 

[WillisV]

Just use Elocone nuts, this is what they are made for:Elocone_Product_Literature