3/4" A325 N bolt-nut penetration 2

[WWTEng]

Should any structural bolt have a complete penetration of the nut or is there some leeway to allow not to? I am looking at some structural connections where the bolt doesn't penetrate the nut entirely.

Can a partial capacity be assumed from partial penetration?

 

[jayrod12]

http://www.eng-tips.com/viewthread.cfm?qid=387020

similar to that link. That one is for anchor bolts but the theory is the same.

 

[KootK]

Yeah, you can get a prorated capacity for partial thread engagement. It's come up here recently too. This document provides some guidance on the calculations as well as some relevant references: Link

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[MikeHalloran]

The usual bolt/nut engagement discussion here centers on how many threads of the bolt must project beyond the nut. A search on 'bolt projection' or similar will find a ton.

The typical question that triggers the discussion comes from someone who has a bolt or stud whose end is flush with the nut, and whoever bought the bolts or embedded the studs in concrete doesn't want to buy and install longer ones.

If your bolt is not getting at least flush with the far side of the nut, you don't _have_ a _structural_ connection.

For your particular unspecified situation, somewhere in the world, you can assume anything you like, but the risk is yours. Did you bet your house already?


Mike Halloran
Pembroke Pines, FL, USA

 

[desertfox]

Hi

In complete agreement with Mike Halloran on this one, I've always advocated the bolt should have at least 1.5 threads past the end of the nut.
If you consider the failure modes for a nut and bolt, its preferable for the bolt to fail as opposed to the threads of the nut stripping which is normally guaranteed provide the whole of the nut is engaged on the bolt.
Now if the bolt is only partially engaged can you be sure the nut won't strip? My advice change is to change the bolts for longer ones.

 

[campbelltc]

WWTEng -

Totally off this topic, but saw your post a few years ago regarding T shaped structural clay tile. I ran into the same thing and did some research on it and found an ad in Sweets Catalog from 1920 that lists Denison Interlocking Tile and it's load bearing capacities:

https://books.google.com/books?id=K...e executive offices guardian building&f=false

Sorry to hijack this thread but thought you might want to see it.

 

[ajh1]

AISC and RCSC mandate that the bolt end be at least flush with the outer surface of the nut.