12d Minimum Anchor Depth Requirement?
12d Minimum Anchor Depth Requirement?
(OP)
I recently had an engineer that I work with ask me if there were any code requires for minimum anchor depths to be maintained. He was specifically asked about 12d (i.e. 12 times the anchor diameter). As far I know the 12d is an old "Rule of Thumb" and is not a current code requirement. Does anyone have any insight into where the minimum anchor depth requirement of 12d originally came from?






RE: 12d Minimum Anchor Depth Requirement?
RE: 12d Minimum Anchor Depth Requirement?
RE: 12d Minimum Anchor Depth Requirement?
RE: 12d Minimum Anchor Depth Requirement?
From: "Burdette, Edwin G"
To: TRAVIS C SMITH
Date: 7/27/2010 10:41 AM
Subject: RE: Is there a Minimum Anchor Depth Requirement by Code?
Travis,
I agree with you that ACI 318 App. D can be used to calculate required depth, and I am unaware of a minimum depth requirement. But it seems to me that there would logically be a minimum depth. As to 12d, I think that came from the old way we used to calculate pull out capacity using a 45 degree cone. And a good rule to assure that the pull out strength would be at least as great as the ultimate strength of the anchor that is, the bolt would break before it pulled out was to embed it 12d. That still is not a bad rule of thumb to assure ductile behavior.
EGB
Edwin G. Burdette
Professor of Civil Engineering
115 Perkins Hall
The University of Tennessee
Knoxville, TN 37996 2010
________________________________
From: TRAVIS C SMITH
Sent: Tuesday, July 27, 2010 10:02 AM
To: Burdette, Edwin G
Subject: Is there a Minimum Anchor Depth Requirement by Code?
Dr. Burdette,
I was wondering if you could help me answer a question? I was recently had an engineer that I work with ask me if there were any code requires for minimum anchor depths to be maintained. He specifically asked about 12d (i.e. 12 times the anchor diameter). As far I know the 12d is an old "Rule of Thumb" and is not a current code requirement. The only code requirement that I know of is that the strength requirements of ACI 318 Appendix D should be met. I would assume that one could use Appendix D to calculate a minimum embedment depth for a give anchor.
Do you have any insight into where the minimum anchor depth requirement
of 12d originally came from?
Thanks for your help.
Regards,
Travis C. Smith, P.E.
Senior Structural Engineer
Mesa Associates, Inc.
10604 Murdock Drive
Knoxville, TN 37932