INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Jobs

Link To This Forum!

Partner Button
Add Stickiness To Your Site By Linking To This Professionally Managed Technical Forum.
Just copy and paste the
code below into your site.

Bolt holes oversized 1/16" or 1/8" for galvanized members

Bolt holes oversized 1/16" or 1/8" for galvanized members

(OP)
When hot dip galvanizing is to be used, does the AISC allow 1/8" oversized holes or is it necessary to stick with 1/16" oversize?  These particular connections are bearing designed but I am also interested in other connection designs are the same (friction, slip critical, etc).

RE: Bolt holes oversized 1/16" or 1/8" for galvanized members

We use bearing connections and galvanized steel angles with holes 1/16 larger than the bolt for 5/8 and 3/4 bolts.

_____________________________________
I have been called "A storehouse of worthless information" many times.

RE: Bolt holes oversized 1/16" or 1/8" for galvanized members

I was thinking that the holes were not threaded since IFRs specified either 1/16 or 1/8 oversize and this would be too large to get threads in.  I was assuming that the holes were for bolts with nuts to connect 2 members either in a bearing type connection or a friction connection.

_____________________________________
I have been called "A storehouse of worthless information" many times.

RE: Bolt holes oversized 1/16" or 1/8" for galvanized members

(OP)
Yes - I meant clearance holes for bearing type connections.  Thanks for the link WillisV.

Another question has come up - are slotted holes allowed for cross bracing of pipe rack type structures, as requested by our erector to make the job of erecting the steel go easier?

RE: Bolt holes oversized 1/16" or 1/8" for galvanized members

Oversized and short slotted holes may be used without regard to direction of load. Long slots can only be used when load is applied perpendicular. Ref. pg 5-271, 9th Edition AISC manual.

It has been my practice to use oversized holes for bracing with A325 SC bolts to allow the erector some adjustment in fitup.

RE: Bolt holes oversized 1/16" or 1/8" for galvanized members

(OP)
Jike - is this for slip critical designs only or can bearing type connections use short slot connections?

RE: Bolt holes oversized 1/16" or 1/8" for galvanized members

It is common practice for one of the connecting pieces to have short slots for easier fitup (even in bearing type simple shear connections).  

RE: Bolt holes oversized 1/16" or 1/8" for galvanized members

(OP)
WillisV -
I appreciate that fact but I'm not able to convince the powers that be to allow it since the AISC manual does not cover it.  The section quoted on page 5-271 seems to be for slip-critical not bearing connections.  In addition, queries on the AISC web site bring up specific Q&A that deem slots unacceptable.

RE: Bolt holes oversized 1/16" or 1/8" for galvanized members

The AISC manual does cover it quite explicitly - see following in 13th edition manual:

Double Angle Connections:  p10-9 to 10-10 - read paragraph on "shop and field practices" - "Alternately, short-slotted holes can also be used."

Single Angle Connections:  p10-123 - "shop and field practices" - ..."play in the open holes or horizontal slots in the angle leg may be used to provide the necessary adjustment to compenssate for mill variation."

etc. etc. etc.  

As long as the slot is not IN THE DIRECTION of the applied load then it is perfectly acceptable in a standard shear connection.  

Also see Item no. 32 in the "57 tips for reducing connection costs" :  http://www.aisc.org/Template.cfm?Section=Technical_Answers&template=/ContentManagement/ContentDisplay.cfm&ContentID=22326   

RE: Bolt holes oversized 1/16" or 1/8" for galvanized members

(OP)
Is it possible to achieve slip-critical connections on hot-dip galvanized members?  Is this covered in AISC?

RE: Bolt holes oversized 1/16" or 1/8" for galvanized members

Yes and Yes.

RE: Bolt holes oversized 1/16" or 1/8" for galvanized members

(OP)
I'll read my 9th and 10th editions again...

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources

White Paper: Agile Product Engineering and Improved Product Outcomes
Today’s product development cycle is fraught with difficulties. Increased demands for complex functionality and reduced product development windows cause engineering teams to borrow practices from the IT industry, swapping outdated serial workflows for a more flexible and collaborative design method known as Agile Product Engineering. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close