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RE: Oversizing Base Plate Holes

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I often specify square plate washers, however thick you want them, with
standard holes.  These are to be set over the anchor bolts and welded to the
base plate in the field.  You can then a standard washer.

Brian K. Smith, P.E.

> -----Original Message-----
> From: James F Fulton [mailto:James_F_Fulton(--nospam--at)RohmHaas.Com]
> Sent: Wednesday, January 17, 2001 8:53 AM
> To: seaint(--nospam--at)seaint.org
> Subject: Oversizing Base Plate Holes
>
>
> I've got a 12000 gal tank, 11'-10" OD,  supported on eight W
> 14x74 legs,
> 8 ft. unsupported leg length.  Each leg sits on a 2 ft. high reinforced
> concrete pier, and the leg base plate is anchored by two 1-1/4"
> anchor bolts,
> A307 or A36 mat'l. I am concerned about fab and construction tolerances,
> paticularly for this tank leg configuration, and want to oversize
> the holes
> in the base plate a reasonable amount to help the situation. The
> suggested
> detail in AISC ASD Manual, on p. 4-130 in Suggested Details,
> recommends the
> hole be oversized by 1/2" for 1" to 2" anchor bolts. So I end up
> with 1-3/4"
> holes for these 1-1/4" bolts. Heavy Hex nuts are to be specified.
> My question
> is the standard washer that will come with these bolts be adequate size
> (thickness and diameter) to span the gap between edge of bolt and edge of
> hole. As a worse case, if the bolt ends up being shoved against
> the edge of
> the hole, the gap could be as large as 1/2". What is an
> appropriate washer
> for this condition ? Thanks for any quidance on this.
>
> Jim Fulton
>
>