Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

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

[Subject Prev][Subject Next][Thread Prev][Thread Next]
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

-----Original Message-----
From: Swingle, Mark [mailto:Mark.Swingle(--nospam--at)]
Sent: Monday, November 15, 1999 5:15 PM
To: 'seaint(--nospam--at)'
Cc: 'mswingle(--nospam--at)'
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.


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