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RE: 97 UBC 1633.2.4 Deformation compatibility - is that a typo?

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Hey, I'm still confused. I know I got into this discussion late, but I am
attempting to work through it now and don't see how increasing the
interstory drift benefits the structure.
The code sets Delta-M as 0.025 times the story height. The Seismic Design
Manual for ICBO gives this figure in inches so that for a 12-foot story
height of 3.6-inches. This seems extremely high considering that past codes
set the limit for story drift at 0.005H or less than 0.72 inches for a
12-foot story height.

What am I missing here? Can you explain it to me in simplistic terms (since
I must be missing something).

I appreciate the help
Dennis

-----Original Message-----
From: Swingle, Mark [mailto:Mark.Swingle(--nospam--at)dgs.ca.gov]
Sent: Monday, November 15, 1999 5:15 PM
To: 'seaint(--nospam--at)seaint.org'
Cc: 'mswingle(--nospam--at)earthlink.net'
Subject: Re: 97 UBC 1633.2.4 Deformation compatibilty - is that a typo?


Thanks, Mike

I see what you are saying.  DeltaM will control in most cases.  If you ARE
at the drift limit for a relatively stiff building (deltaM = 0.025), then
the deltaM will control since it is much larger.

Mark

------------------------------------------
Michael Valley wrote:

Mark: That is NOT a typo. Instead, this sets a lower bound on the demand
displacement. In other words, no matter how stiff you think your lateral
force resisting system is, you must consider an interstory drift of 0.25%
for deformation compatibility. -Mike