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RE: OSHA 4-bolt column anchorage

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There is an AISC Advisory dated March 12, 2001 which states all columns must
be designed and fabricated with a minimum of (4) anchor rods, however
"posts" are excluded form the 4-anchor-rod requirement.

Definition of a post, from 'Safety Standards for Steel Erection -
"Post."  This term is defined to mean a structural member with a
longitudinal axis that is essentially vertical, that: (1) Weighs 300 pounds
or less and is axially loaded (a load presses down on the top end), or (2)
is not axially loaded, but is laterally restrained by the above member.
Posts typically support stair landings, wall framing, mezzanines and other

This exception is also talked about in the AISC Advisory mentioned above.


-----Original Message-----
From: Charley Hamilton [mailto:chamilto(--nospam--at)] 
Sent: Monday, February 06, 2006 11:43 AM
To: seaint(--nospam--at)
Subject: Re: OSHA 4-bolt column anchorage

Dave -

Bill is right:  it's a federal OSHA ruling.  As far as I
understand, there are no exceptions in 29 CFR 1926.755.
The rule can be found here:

Take a look at and search for "base plate anchorage".
It brings up quite a bit of info about the why's and wherefore's
of the 4-bolt rule.  For example:

Scroll down to "Section 1926.755 Column Anchorage" and you can see some of
testimony that was offered.

Personally, I suspect it would be greater total cost to go to
(e.g.) two bolts and guying to provide stability than to simply
design in the four bolts from the get-go.  Adding a process (guying
and un-guying each column) to the erection seems like it would add
cost, mostly through labor.  You might save a bit on the labor of
installing half the anchor bolts, but that seems like less labor to
me than installing and removing the guys.  Also, it seems that the
guys could potentially be in the way during erection of the girders.

Just my $0.02,


Charles Hamilton, PhD EIT               PGR
Department of Civil and                 Phone: 949.824.3752
     Environmental Engineering           FAX:   949.824.2117
University of California, Irvine        Email: chamilto(--nospam--at)

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