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RE: Sole plate anchor rod holes

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It does matter in this case.  These anchor rods were designed to transfer longitudinal loads from the superstructure to the abutment.  During design, I didn't think about how much the holes would be oversized.  Now, I think I should account for the possible movement of 0.5" for these "fixed" bearings.  Is this too conservative to do this?  As I'm sure you are aware, there will be significant differences in the elastomeric bearing with movement as opposed to being fixed.
 

Chris Towne, P.E.
Chapman Technical Group
200 Sixth Avenue
St. Albans, WV 25177
304-727-5501

-----Original Message-----
From: S. Gordin [mailto:mailbox(--nospam--at)sgeconsulting.com]
Sent: Friday, September 16, 2005 1:15 PM
To: Seaint@Seaint. Org
Subject: Re: Sole plate anchor rod holes

Bridges are different from the building columns, with considerable lateral forces (earthquakes, wind for light bridges, stream flow pressure, etc.) may be accompanied by somewhat lower gravity loads.  In these cases, the size of the anchor bolt holes, the precision of the anchor rod installation, and even the edge distances (particularly, for slotted holes) may matter greatly.
 
For bridges, I usually go by AISC 9th Edition (2" dia holes for 1.5" dia rods, 1/8" max deviation/tolerance for rod installation).  Not to jinx it, but so I far did not have problems with the bridge/anchor installers. 
 
Steve Gordin SE
Irvine CA
 
----- Original Message -----
Sent: Friday, September 16, 2005 9:59 AM
Subject: RE: Sole plate anchor rod holes

In 2003 AISC updated (AISC Manual of Steel Construction 9th ed pp 4-130)
table, the Oversize Hole for 1 1/2"dia to as much as 2 5/16" if a heavy
plate (5/16 to 1/2) washer is used.  All this is being driven by common
practice of misplacement of anchor bolts by concrete trades (not
conforming to AISC Code of Std Practice 7.5.1). 
Also, anchor bolts exert relatively small lateral load on base plates,
therefore the only edge requirement is: enough steel is left between the
edge of the plate and the closest edge of the hole so the drill or punch
will not drift as the hole is made (AISC Table J3.5 do not apply since
"tear-out" is not a problem). If your application does apply lateral
load on the base plates this is a different situation and should be
reviewed.  See the AISC site for the discussions on misplaced anchor
bolts and suggested oversized holes in base plates.

Dean Briggs

-----Original Message-----
From: dave lowen [mailto:jatech(--nospam--at)kwic.com]
Sent: Friday, September 16, 2005 10:03 AM
To: seaint(--nospam--at)seaint.org
Subject: RE: Sole plate anchor rod holes

According to the AISC, the shop is correct. BUT, you may make them
smaller.
Yu da boss.

Regards,
Dave Lowen
Jarvis
V 519 587 5797
F 519 587 5138
E jatech(--nospam--at)kwic.com

Waterloo
V 519 749 9468
E jatech(--nospam--at)bellnet.ca

-----Original Message-----
From: Chris Towne [mailto:ctowne(--nospam--at)chaptech.com]
Sent: September 16, 2005 12:02 PM
To: seaint(--nospam--at)seaint.org
Subject: Sole plate anchor rod holes

For you bridge engineers...

We are reviewing shop dwgs and the fabricator wants to put a 2" dia.
hole in
the bearing sole plate for a 1.5" dia. anchor rod.  This seems
excessive.
Does anyone have any suggestions?

The bridge is a simple span, 48' long, one end fixed and the other end
expansion with no anchor rods.  The bearings are steel reinforced
elastomeric pads.

Chris Towne, P.E.
Chapman Technical Group
200 Sixth Avenue
St. Albans, WV 25177
304-727-5501


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