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RE: base plates subject to uplift

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I recently asked Charlie Carter a similar question.  His response was as
	AISC Design Guide #10 (page 16, section 4.2.5) says: " a rule of
thumb, it is suggested that the thickness of the washers be a minimum of 1/3
the diameter of the anchor rod, and that the length and width of the washers
equal the base plate hole diameter plus one inch <as a minimum>."  If you
get abnormally large holes (like in the case of a field fix), you may have
to use thicker washers.  RCSD prohibits stacking washers to get the 5/16
thickness because you don't get as much bending strength with two as you do
with one of the total thickness.  ...I don't think a hardened washer is
required and the thickness you'd wind up with according to the above rule of
thumb aren't generally covered under ASTM F436 anyway.  So in the end,
they're normally just common plate washers."

Roger Davis
SDS Architects, Inc
205 N. Dewey Street
Eau Claire, WI 54703

-----Original Message-----
From:	PFFEI(--nospam--at) [mailto:PFFEI(--nospam--at)]
Sent:	Friday, June 16, 2000 1:41 PM
To:	seaint(--nospam--at)
Subject:	base plates subject to uplift

What is the maximum oversize bolt hole diameter for a base plate subject to
uplift? AISC allows 1-5/16" diameter holes for a 3/4" diameter bolt.  This
larger than the dimension  across the flat of  a 3/4" diameter bolt of
1-1/8", and would seem to have a significant impact on the capacity of the
connection.  Limiting hole diameter to 1/16" oversize seems overly
restrictive for field fit up with anchor bolts.  How effective are hardened
washers to transfer upfilt forces?
Paul Franceschi, S.E.