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RE: UBC '97 Sec 1633.2.4 Deformation compatibilty

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You have misplaced the decimal point in the second condition.  Section
1633.2.4 of the 1997 UBC states the second condition as 0.0025 times
the story height.  This is not a typographical error.  The intent is
to require some measurable deformation capacity even when the lateral
system is very stiff (and thus has delta_M much smaller than the
allowable drift).

Without this limit, some designers of concrete shear wall buildings
might have unrealistically low deformation demands due to the real
wall stiffness and an assumption of infinitely rigid diaphragms.

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Michael Valley, P.E., S.E.                   E-mail: mtv(--nospam--at)skilling.com
Skilling Ward Magnusson Barkshire Inc.              Tel:(206)292-1200
1301 Fifth Ave, #3200,  Seattle  WA 98101-2699      Fax:        -1201

-----Original Message-----
From: Attila Beres [mailto:Attila.Beres(--nospam--at)Englekirk.com]
Sent: Wednesday, May 24, 2000 5:26 PM
To: Seaint Listserver posting
Subject: UBC '97 Sec 1633.2.4 Deformation compatibilty


If I am reading this right, this check asks for using the interstory
deformation value to be considered as the greater of :

1. DeltaM, as calculated in accordance to Sec 1630.9.2 (0.7*R*DeltaS)

2. 0.025*story height.

When would the first condition govern? The inelastic story drift
ratios are limited to max. 0.025.

Am I missing something, or the first condition is redundant?
......................................................................
.....
Attila Beres