It comes down to a matter of how you interpret OSHA 29 CFR 1926. In terms of anchor bolt requirements, the OSHA document differentiates between “posts”, which can have two anchor bolts, and “columns” which require four. The problem is that the document does not clearly define what they mean by a post and a column, other than stating that a “post” cannot weigh more than 300 pounds. My understanding (based on a close review in the context of developing some educational aids) is that the OSHA document considers a “column” to be part of a primary framing system (your main structural load-bearing frame, moment frames, etc.) and a “post” part of a secondary framing system (like a mezzanine). I’d consider a stair tower to be secondary and its vertical supports as “posts” and use the two bolts.
Gary
Gary J. Ehrlich, PE
Program Manager, Structural Codes & Standards
National Association of Home Builders (NAHB)
ph: 202-266-8545 or 800-368-5242 x8545
fax: 202-266-8369
From: Micayas, Julius [mailto:jmicayas@riverconsulting.com]
Sent: Wednesday, September 26, 2007 12:51 PM
To:
Subject: no. of anchor bolts
Due to some clearance problem we are inclined to provide two anchor bolts instead of four for our stair tower base plate. The load or the capacity is not an issue, two-bolt is adequate. My only concerned was back in 1999 when I did a retrofit project they told me that 2-anchor bolts is no longer acceptable (i.e. for construction safety…)
I’d like to know what part or chapter this be that deprive me to do so.
Thanks
Engr. Julius Micayas
P.E. license no.32969
Senior Lead Structural Engineer
Phone - 504-841-3014 (direct)
504 837-5275 (office)
Fax - 504-837-2986