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Re: Engineers involved with UBC

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Thanks for the insight in to the thinking.  However, I think as the years
have progress the "long form" and "short form" have separated.  Based upon
the study that I had done, the wind loads from UBC 97 do not match those
derived from ASCE 7-95.  And the UBC 97 still does live as an out the use
of ASCE 7-95 instead of the wind provisions in the actual UBC code.
However, we found that the ASCE loads were smaller than the UBC loads.
Therefore, we elected to used the BOCA loads which were more conservative.
And my personal philosophy is that while I might be a little to the
liberal side in politics, I am DEFINITELY conservative when it comes to
engineering!  ;-)

Scott

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Scott E. Maxwell, SE, PE
Structural Engineer

BEI Associates Inc.
601 West Fort Street
Detroit, MI  48226

Telephone: (313) 963-2300                              
Fax:       (313) 962-4269

Email for Business: 
Email for Personal: smaxwell(--nospam--at)engin.umich.edu
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On Wed, 22 Mar 2000, Charles Greenlaw wrote:

> Scott, I see what you mean, where there are moment frames for both
> orthogonal directions of the structure, and the oblique resultant wind load
> makes for bi-axial bending.
> 
> I doubt that such a scenario was contemplated in the pre-1982 UBC Wind
> provision rewrite; I don't recall it being aired. Much of the research used
> at that time was done for the Metal Bldg Mfrs Assn, and two-way moment
> frames seemed not to be their concern. ANSI had just compiled a complex wind
> code and reportedly pressed for its adoption as is into model codes, and the
> UBC effort was to simplify it for ordinary use, like a "short form" in tax
> returns, but embracing the long-form ANSI A58.1 version as a fall-back at
> the option of the code user. The EIA code for towers was allowed as another
> option, as "an approved national standard." Perhaps the complete ANSI
> version speaks to side walls concurrent with windward and leeward walls. The
> SEA of Washington has an excellent commentary on the UBC wind provisions,
> and it says that the ANSI A58 is now ASCE-7.  (Hope I got all the acronyms
> right this time.)
> 
> Yet the UBC still requires consideration of wind coming from any horizontal
> direction, which includes oblique directions. How one does the analysis for
> this is not suggested however, unlike for oblique seismic directions. When
> the short form doesn't cover one's situation, then resort to the long form
> and/or to basic principles is intended.
> 
> What's missing in seismic codes is two things: a long-enough simple short
> form method for routine situations, like UBC wind provisions, and the spirit
> among those who count to allow such a thing to exist, unlarded with grudging
> penalties.
> 
> Charles Greenlaw SE  Sacramento CA
> 
> At 02:25 AM 03/22/2000 -0500, you wrote:
> >Charles,
> >
> >I understand this thinking for do the components and cladding
> >design...i.e. either windward or leeward will always govern over a
> >"sidewall" pressure, but there are some scenarios that might create
> >problems with this method when doing the main force resisting system.  For
> >example, say you have a large industrial plant (i.e. an automobile plant
> >building) that is rather long and has several expansion joints along the
> >length of the building.  The end portions of the building could have a
> >wind scenario where there is windward pressure on the one wall, leeward on
> >the other side of the building, sidewall pressure on one side, and nothing
> >(interal) at the expansion joint.  In the case of an industrial building
> >where the trusses are being used a moment frames, this could produce
> >bi-axial bending on the columns.  The UBC code does not appear to address
> >this type of situation adequately.
> >
> >Maybe this might help explain why the question was asked.
> >
> >Scott E. Maxwell, SE, PE
> >Structural Engineer
> 
> 
>