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Re: UBC '97 Sec 1633.2.4 Deformation compatibility

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With all due respect, I disagree. My opinion is that it is (or should be)
a typo. If the inelastic interstorey drift is 2.5% (limited from sec.
1630.10.2) then the philosophy is that the non-lateral-force-resisting
members can undergo this displacement elastically as well without
collapsing. You normally don't detail these members to the same stringent
requirements as the lateral-force-system.  0.25% seems ridiculously low to
me as a design value for this compatablity check, but maybe I'm completely
misunderstanding this.

Mike Valley wrote:

> To reiterate, 1997 UBC Section 1633.2.4 does NOT give you a CHOICE for
> the deformation.  It says, "Expected deformations shall be determined
> as THE GREATER OF ... delta_M... or the deformation induced by a story
> drift of 0.0025 times the story height."
>
> The second condition (0.0025) is NOT a typo of 0.025.  Instead it
> serves as a minimum deformation capacity compatibility checks for very
> stiff systems.
>
> - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
> 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: Steve Hiner [mailto:shiner(--nospam--at)folsom.ca.us]
> Sent: Thursday, May 25, 2000 10:11 AM
> To: 'seaint(--nospam--at)seaint.org'
> Subject: RE: UBC '97 Sec 1633.2.4 Deformation compatibility
>
> Per UBC 1630.10.2, DeltaM shall not exceed 0.025 times the story
> height for
> structures with T < 0.7 seconds ...
>
> UBC 1633.2.4 gives you the choice to either use the expected
> deformation
> based on your "calculated" DeltaM, or the expected deformation
> assuming that
> DeltaM is equal to the maximum allowed value of 0.025 times the story
> height.
>
> Steve Hiner, SE
> Folsom, CA
>
> ps - I appear to have a misprint in my 1998 "California" Building Code
> for
> Section 1633.2.4 (p. 2-19) where the 1st paragraph, 2nd sentence reads
> '...
> 0.0025 ...' rather than '... 0.025 ..."
>
> -----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
>