Bolt Shank Length

[SteelPE]

I have a project where the we have some connections that were designed using SC bolts. I am wondering if there are any AISC provisions that indicate the amount of unthreaded shank allowed in the connection.... and if there are, then where can I find such provisions.

I have skimmed through the RCSC information in the back of the AISC and can't really find anything.

 

[StrPE]

Thread lengths are provided on page 7-80 of the 13th Edition AISC manual. This length is constant for a given bolt diameter. Once you know the bolt length subtract the thread length to get the unthreaded shank.

 

[connectegr]

Same information is in the RCSC spec. fig. C-2.2

http://www.FerrellEngineering.com

 

[connectegr]

There is also a bolt length calculation App for iPhone

http://www.FerrellEngineering.com

 

[SteelPE]

Is there anything that states the amount of shank allowed in a SC connection. Say if I have a 3/4" dia 2" long bolt that connects 3/4" of material together..... then I would have 2"-1.375" = (3/4"-5/8") = 1/8" thread inside of the connection. How much thread is allowed?

 

[WillisV]

Why does it matter?

 

[StrPE]

Only in bearing bolts does it matter, i.e. "N" vs "X". Otherwise it does not matter how many treads are in the faying surface.
There is no code specifying the number of threads allowed.

 

[SteelPE]

WillisV,

Lets say you have a 3/4" dia 2" long bolt in a slip critical connection. You now have a shank length of 5/8". If the connected parts you are connecting are less than 5/8" you can no longer torque the bolt properly because the nut is hitting the shank. Therefore your connection is no longer SC. At least that is how I look at it.

 

[WillisV]

Then put on a washer behind the head...

 

[StrPE]

The normal installation procedure for this case is to add washers so the nut does not bottom out. Washers can be installed under the head and/or nut. This is different than threads in the faying surface.

 

[ToadJones]

dont they make bolts that are fully threaded for this?
connectegr?

 

[ATSE]

A325-T

 

[Dinosaur]

Yes, minimal length bolts are often supplied fully threaded and they carry the designation indicated by ATSE, with the "-T" indicating fully threaded. Only short bolts ar emade this way typically when A325 or A490 are specified. If you need a special threaded length, you will probably need to look at A449 material.