] [Thread] [Date] [Author]

["Dave Handy" <dhandy(--nospam--at)trg.ca>]

Rob:
Are you modelling the walls with hand calcs or with FE software? I would 
think that the requirement to model as per chapter 21 would be related to 
hand calcs. The FE software "dependent upon input, should" model somewhat 
close to reality if the entire tube was input. The appropriate amount of 
cracking with the sections would have to be input for the Ieff value.
Dave
btw I don't have the relevant ACI handbook but am making a reasonable 
assumption as to what it contains. I have CSA handbooks


----- Original Message ----- 
From: "Rob Still" <robs(--nospam--at)adcengineering.com>
To: <seaint(--nospam--at)seaint.org>
Sent: Tuesday, October 04, 2005 9:09 AM
Subject: Concrete Shear Wall / Shear Cores


I have a question in modeling concrete shear walls configured in a tube,
like that found around a stair or elevator. My question is related to a
possible difference in how the building should be modeled to calculate
drift, and how it should be modeled to design the walls to ACI.

ACI chapter 21, limits the effective flange width of a shear wall to 1/4
the wall height. If I use this criteria the "flange" of the tube is not
fully effective, thus the structure should not be modeled as a tube, but
two "C"
shaped sections.

The question arises in that Two "C" shaped sections potentially have far
less moment of inertia than the tube section, depending on how much of
the tube flange is effective in the "C's".

So should the building be modeled assuming tube behavior, or "flanged"
behavior for calculating drift?
It appears to be evident that by ACI that it should be modeled using
"flanged" behavior.

Furthermore, if Chapter 21 is not applicable should the effective flange
be limited by the same criteria as if it were a "Tee Beam?"

Any comments / assistance would be greatly appreciated.


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