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RE: Thick Concrete Walls, no non-linear EQ dissipation.

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Em represents the code's prediction of the maximum elastic force that some
structural elements could possibly see IF the buidling was designed to
behave in a ductile manner. For a building subjected to the code level
earthquake to behave in a completely non-ductile manner. you would use an
R=1 (I have no idea why you would want to, though, for the code assumes or
requires the ductility regardless).

The PCA publication "Design and Control of Concrete Mixtures" touches on
most of the items you listed. The UBC ultimately will dictate the values you
use and specify for strength, air entrainment, and thermal R values.
Moisture control and sealants probably don't even have any code
requirements, more of a standard construction practice or a commerical
proprietary thing.    

-----Original Message-----
From: David Merrick [mailto:mrkgp(--nospam--at)winfirst.com]
Sent: Friday, March 07, 2003 6:24 PM
To: SEAINT
Subject: Thick Concrete Walls, no non-linear EQ dissipation.


I considering a design with thick 16" concrete walls, for a two story home.
Design minimums for steel detailing and concrete strength as defined in
section 1921 of the 1997 UBC are as stated in 1921.2.1.1 "for design
forces...earthquake motions...basis of energy dissipation in the nonlinear
range of response." What force level is required to be in compliance with
1921 by not using dissipation in the nonlinear range? I suspect an omega
factor of 2.8 or more, or there is no such provision as a non-ductile
condition.

Does Em represent a seismic force that is not reduced by using dissipation
in the nonlinear range? That is set E=omega*(ro*Eh + Ev) and Em=(omega^2)Eh
and use also use a maximum reliability/Redundancy factor of 1.5

What is the best source for air entrained concrete specifications, strength,
thermal R values, moisture resistance, placement problems and recommended
sealant?

David Merrick, SE




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