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RE: UBC: How Do You Interpret 1997 UBC P

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Bill:

Be careful with live load reduction for parking garages.  I know that no
reduction is permitted in the IBC for "passenger car garages" except
"...the live loads for members supporting two or more floors are permitted
to be reduced..."  I seem to recall that most (or all) of the model
building codes have a similar provision...that is one is not permitted to
reduce the live loads for parking decks.

Regarding your question about live reduction in general, I am not aware of
any other method of reducing live loads except by using "tributary" areas.
The IBC does permit two different methods of determining the allowable
reduction of live load, but both are based upon "tributary" area.

HTH,

Scott
Ypsilanti, MI

On Wed, 6 Mar 2002, Bill Polhemus wrote:

> My question wasn't regarding the rationale for live load reduction due to
> tributary area-I understand that.
>
> My question was, since several people mentioned LL reduction "by tributary
> area" specifically, is there some provision for LL reduction in the code due
> to any other reason?
>
> Also, the attorney does seem to sincerely want my professional opinion no
> matter what. I should mention that he represents an insurance carrier for
> the OWNER. They apparently carry an "excess damages liability" policy that
> would pay the cost for the repairs to the parking structure-which are very
> real, and very perplexing-OVER AND ABOVE that which the Engineer's E&O would
> pay.
>
> They are trying to determine whether this was a true "omission" or if the
> Engineer's "fault" was in fact minimal. The Engineer appears to be
> maintaining that "we designed per the Building Code" (UBC 1994 in this case,
> although for some reason the Engineer used 1991 UBC which had been
> superceded by the time the drawings went to permitting-a minor point since
> it doesn't appear there's enough difference at least in the Live Load
> provisions between the two codes to matter. Anyone who begs to differ with
> that, please let me know), and thus they are absolved from liability on that
> account.
>
> However, it appears from a reading of the Code, that "weasel words" might
> carry the day. IMO, there is reason to suggest that "due diligence" was not
> pursued in this case. A survey of the literature reveals plenty of reasons
> to go with a Live Load in parking structures of this type above the Code
> minimum. I say "IMO" because I know how I approach stuff like this: I VERY
> CAREFULLY determine if the loads seem acceptable before I proceed, Building
> Code minimums notwithstanding. And it was relatively easy with a couple of
> days' inquiry (including in this forum, which once again has proved its
> value FAR BEYOND any reasonable expectation, thanks to the erudite-as
> always-comments received from all of you) to discover there is a rational
> basis for going with AT LEAST the 50 psf distributed load with NO reduction
> due to tributary area, and with a higher concentrated load as well.
>
> The kicker is the popularity over the past decade of the super-heavy-duty
> SUV and similar "pleasure vehicles."
>
> In all honesty I can see it both ways, since the state of our knowledge
> about loading for parking structures has only recently caught up with the
> reality of the past decade.
>
> At the root of this dispute, the question seems to be "how much 'due
> diligence' is actually 'due'?" As someone who detests prescriptive codes,
> and who doesn't worry about clients' turning me down (even though I'm just a
> humble SOHO) because Fred whom they've used for the past twelve years ALWAYS
> gives them a cheaper design than that, it just ain't worth the pain and
> agony of just such a dispute as this EOR has been undergoing for the past
> four years (that's how long the matter has been in dispute).
>
> Of course, since the owner of this parking structure is a rather prolific
> developer of commercial and multi-family residential property, I'm sure they
> have in the past represented a lucrative source of work for the EOR, and
> based purely on supposition I would guess that one reason they've enjoyed
> this long relationship is the owner has come to rely on the EOR's
> willingness to skin it close to the bone on his designs.
>
> So the owner has himself to blame in part for this debacle, though I feel
> certain that with an attorney on his side to reassure him (and I've read
> some of the depositions he's been involved in; he is a REAL jerk), that
> thought would NEVER cross his mind.
>
> Business is War.
>
>
> William L. Polhemus, Jr. P.E.
> Polhemus Engineering Company
> Katy, TX, USA
> Phone (281) 492-2251
> FAX (281) 492-8203
> email bill(--nospam--at)polhemus.cc
>
> -----Original Message-----
> From: Roger Turk [mailto:73527.1356(--nospam--at)compuserve.com]
> Sent: Wednesday, March 06, 2002 12:18 PM
> To: seaint(--nospam--at)seaint.org
> Subject: RE: UBC: How Do You Interpret 1997 UBC P
>
> Bill,
>
> The live load reduction rationale is based on the assumption that as
> tributary area increases, the likelihood of the entire area being loaded the
> specified amount diminishes.
>
> * * *
>
> BTW, does the lawyer want you to determine the cause of the problem(s) or is
> he/she focusing on the LL reduction.  If the latter, the attorney is looking
> for a whore on whose testimony the attorney can base his/her case.
>
>
>
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