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Re: UBC: How Do You Interpret 1997 UBC Paragraph 1607.1?

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Bill:

I would say in response to item #1...first, you determine the intended use
of the parking structure.  For example, is the intended use of the
structure only for passenger cars and maybe a full-size van or pick-up
truck?  Or can it also accommidate buses, RVs, etc?  If it is the former
(and there is something physical that can prevent an RV from parking on
in the structure...such as the typical floor-to-floor heights of most
parking structures around here), then the 50 psf as prescribed by most/all
the codes would be fine since those are the type of vehicles that were
used to arrive at 50 psf and the point loads in the code.  If it is
expected (or possible) that something other than a "standard passenger
vehicle" could park in the structure, then a seperate analysis should be
done to determine if a higher uniform load and/or point load should be
used in the design.

Basically, the code is saying you as the engineer shall determine what is
the appropriate load for the expected (or possible) use or occupancy but
that that load cannot be less than the values listed in the code, which
would be for "normal" circumstances.  So that implies (to me at least)
that if your circumstances are not "normal" then you should be using
higher live loads than outline in the code.

HTH,

Scott
Ypsilanti, MI

On Tue, 5 Mar 2002, Bill Polhemus wrote:

> This came up in a discussion with an attorney today.
>
> The referenced paragraph states:
>
> "Live loads shall be the maximum loads expected by the intended use or
> occupancy but in no case shall be less than the loads required by this
> section."
>
> Now, in the case that I'm consulting on, the EOR has repeatedly denied all
> responsibility from problems with a parking deck structure based on the fact
> that "they used the loads prescribed by the building code."
>
> However, one line of inquiry has been that the loads applied by
> "pleasure-type vehicles" possibly exceed those prescribed in 1997 UBC Table
> 16-A and in 1607.3.3 "Concentrated Loads".
>
> This leads to two questions that I'd like to be able to answer succinctly
> for my client the shyster:
>
> 1) How does one determine if "the maximum loads expected by the use"  exceed
> and should take the place of "loads required by this Section [i.e. UBC
> Section 1607 "Live Loads"]?
>
> 2) Assuming that such a determination must be made, how have such loads been
> arrived at?
>
> Regarding the second question in particular I have noticed that ASCE
> publishes a "Design Live Loads for Parking Garages." I have ordered this
> publication, but in the meantime the abstract published on the ASCE website
> mentions that the publication (which appears to be a monograph) concludes
> that the 50 psf prescribed in UBC could rationally be reduced to about 40
> psf, but that in many (most?) cases the standard reductions allowed by the
> Code should not be taken. Anyone have any comments on this?
>
>
>
> 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
>
>
>
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