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Re: Oversize Holes in Base Plates - New AISC Manual

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I am actually on both sides of the fence these days (is that really possible?).  I have heard about the lead filling of holes too.  I wonder what the allowable bearing stress is on lead (not very much is what I would guess).
I think the bottom line is that no amount of oversizing will accommodate a sloppy concrete contractor's misplacement of anchor rods.  I believe the erectors like the extra hole size that are now the latest "maximums" but keep in mind that you now need a plate washer under the base plate if you are using leveling nuts.  When I design column bases and there is any significant shear, I will use shear lugs and not field weld the plate washer above the base plate.  If the loads are light, I will field weld the plate washer to the base plate.
----- Original Message -----
Sent: Friday, March 17, 2006 4:43 PM
Subject: RE: Oversize Holes in Base Plates - New AISC Manual

Hi Ken,


As I'm frequently the EOR specifying baseplate hole sizes, I'm open to your comments/recommendations on this.  I can design-in accomodations for any hole size and would like to hear from others on the "other side of the fence".  I met an old engineer once and he told me he used to design oversize (beyond AISC recommendations) baseplate hole sizes and it was common at the time then to fill the annular space between the anchor and edge of holes with molten lead.  Then cover it all with a plate washer.  They didn't weld the plate washer.  Ya learns sumthin' every day.




Bob Garner, S.E.


From: Ken Peoples [mailto:kspeoples(--nospam--at)]
Sent: Friday, March 17, 2006 1:37 PM
To: Seaint; Steel Detail
Subject: Oversize Holes in Base Plates - New AISC Manual


Sorry if this has already been discussed, but I just received my new AISC Manual (13th edition) and someone in my office pointed out to me that the table listing the recommended anchor rod hole size (Table 14-2 in the new manual - page 14-21) now calls these out as the Recommended Maximum Sizes for Anchor-Rod Holes in Base Plates.  This used to be the Recommended Hole Size (not maximum).  When doing detailing work for the last couple years we were always fighting with the EOR trying to get anchor rod placement corrected to take into account the "new" recommended hole sizes per AISC.  I guess we now will live with what the EOR has on their drawings (assuming that the holes are at least what used to be in the ASD 9th Edition) - unless the fabricator wants us to try for the larger holes.



Best regards,


Kenneth S. Peoples, P. E.


Lehigh Valley Technical Associates, Inc.
1584 Weaversville Road
Northampton, PA 18067


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