Thread embedment required for bolt in tension

[EngDM]

Hi all,

A simple question that I have never really thought about, but if you have a bolt in tension are there any checks as far as the threads are concerned? Is there a codeified minimum number of threads (or length) to engage before getting full capacity of the bolt in tension? Is it just to the end of the standard nut size (I.e. that is how the nut lengths were determined and standardized)? Is there an equation in the event that you are not fully into the nut?

This question is moreso for tension requirements, not the intersected vs not intersected shear plane checks.

 

[jhnblgr]

https://www.aisc.org/globalassets/modern-steel/archives/2014/12/si.pdf

https://www.aisc.org/globalassets/aisc/publications/standards/a348-20w.pdf

 

[SWComposites]

the general rule of thumb is min of 3 full threads.
and the nut material/type needs to be strong enough to fail the bolt in tension.

 

[Tomfh]

Codes often require at least one thread beyond the nut.

One thing I've noticed in practice is that if a nut and bolt aren't well machined that the nut can slip anyway, yielding the threads before yielding the bolt.

 

[HTURKAK]

I remember for structural applications (Research Council on Structural Connections Specification requirement is that the end of the bolt be at least
flush with the face of the nut).
Common practice at least 2 threads after nut.
There are previous threads for this subject.
One of them,

Standard for how many threads to be out from a nut​