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Re: Perforated shear wall uplift
- To: seaint(--nospam--at)seaint.org
- Subject: Re: Perforated shear wall uplift
- From: chuck utzman <chuckuc(--nospam--at)pacbell.net>
- Date: Thu, 02 Feb 2006 13:01:17 -0800
We don't need to get snarky ;o)|
It is an empirical method not an analytical one. If those big,
unreinforced openings make you queasy don't use it. Reinforced openings
& some arithmetic make me comfortable here in the backward land of
the 1997 UBC & occasional earthquakes but YMMV.
Chuck Utzman, P.E.
Jason, I think you're trying to be logical when
what you should be doing is just unquestioningly following the code.
(Is my sarcasm coming through?)
If the code says "do it this way because that's the way we tested it"
there's no other reason. "It's just policy." I don't know much about
the IBC, but I assume it also requires plate washers on anchor bolts,
as does the UBC, which are intended to help reduce plate splitting due
to plywood prying in shear walls.
So does everyone design their anchor bolts for combined tension and
Ralph Hueston Kratz, S.E.
Richmond CA USA
In a message dated 2/2/06 11:40:55 AM, jason.christensen(--nospam--at)es2eng.com
So how does one transfer the
uplift force through plywood to plate connection with out causing cross
grain bending in the plate?
Other than using 3 1/2” or 5 1/2” plate washers for 2x4 or
From: Eli Grassley
Sent: Thursday, February
02, 2006 12:09 PM
Subject: RE: Perforated shear
The anchor bolts (not the end holdowns) need to be designed
for a “uniform uplift equal to the wall shear.” Your example of a 10’
wall with 500plf shear gives you 5000# of total uplift. That gets
distributed out to all of the anchor bolts along the length of the
wall. If you have 5 anchor bolts, they each see 1000#. The
overturning holdown forces are a completely separate issue.
This is the code language for designing a “perforated shear
wall.” It is my understanding that this requirement is worded that way
because that is how the testing apparatus was set up when they were
gathering data to make Table 2305.3.7.2 (shear capacity adjustment
~~ Eli G
Sent: Thursday, February
02, 2006 10:21 AM
Subject: Re: Perforated shear
In a message dated 2/2/06 10:12:48 AM, HoodMO(--nospam--at)ci.anchorage.ak.us writes:
2003 IBC section 23053.7.2.6 indicates that "perforated
bottom plates at full height sheathing shall be anchored for a uniform
uplift force, t, equal to the unit shear force, v." Where v is the shear
force for which the bottom plate shear transfer has to be designed.
I have no answers, only more questions. Does this mean that in a shear
wall designed to resist 500 plf must have uplift resistance of 500#?
Or if the wall is 10' long it must have uplift resistance of 5,000#?
And if it's 100' long, 50,000#?