RE: ASCE 7-95 question...[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: "'seaint(--nospam--at)seaint.org'" <seaint(--nospam--at)seaint.org>
- Subject: RE: ASCE 7-95 question...
- From: "Connor, John A NWK" <John.A.Connor(--nospam--at)nwk02.usace.army.mil>
- Date: Wed, 19 Jul 2000 15:25:55 -0700
One thing to keep in mind, if your building is 60 feet or less, you are not forced to design the main force resisting system as a "low rise". You are permitted to use figure 6-3, and design it as a building of "all heights" (non-low rise). I find Fig 6-3 easier to work with than Fig 6-4, so I design all of my low-rise buildings this way.
As for a reason why the coefficients are not equal, maybe it has to do with the wind component that is coming in from the skewed direction (fig 6-4). Fig 6-3 only has wind in the directions of the principal axis.
Some FYI: in ASCE 7-98, Fig 6-4 is tabled the same as 7-95.
I have never sat down and compared the results of fig 6-3 to 6-4. Does anyone know if the results vary significantly between methods?
John Connor, PE
Kansas City, MO
From: Scott E Maxwell [mailto:smaxwell(--nospam--at)engin.umich.edu]
Sent: Wednesday, July 19, 2000 3:11 PM
Subject: ASCE 7-95 question...
I have a question for anyone out there who is familiar with ASCE 7-95. I
am computing the main wind force loads for a building that is under 60 ft
(low rise). So I am using ASCE 7-95's "low rise" method. I am in the
process of determining the External Pressure Coefficients (GCpf) per
Figure 6-4. I am looking at CASE A. My roof slope is 0 degrees. So per
Figure 6-4, the coefficient would be -0.69 for zone 2 (windward roof) and
-0.37 for zone 3 (leeward roof). Now this does not make sense to me. If
my roof is flat (i.e. 0 degrees) shouldn't both of these coefficients be
the SAME? This is not consist with the method for non-low rise buildings
(the cofficients are the same for roof with 10 degrees or less).
Also, another dumb question...how does one obtain a roof with a slope of
90 degrees? <grin>
Scott Maxwell, PE, SE
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