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RE: UBC 97 vs NBCC 95

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as far as I know the NBCC has a better and more accurate approach in wind design and analysis compared to UBC 1997. as you IBC (2003) is the code that is adopted by most states and eventually will be adopted by almost all states. IBC has a much more comprehensive approach toward wind analysis and design which actually makes the analysis complicated. your next question in regards to lower values compared to table 16-F is also related to the fact I mentioned above.
I think over all you'll get higher wind loads with NBCC vs. UBC.

P.S. California does not use UBC 1997 and uses CBC (California Building Code) 2001. The plan is to adopt IBC by 2007 .

Khashayar (Casey) Hemmatyar, PE

[Hemmatyar, Casey]
From: Avicpeng [mailto:vicpeng(--nospam--at)]
Sent: Friday, August 26, 2005 9:28 AM
Subject: UBC 97 vs NBCC 95

Question for those doing both systems.

I'm reviewing a tent design for use in BC, Canada, and I am comparing "specified" wind loads developed from NBCC guidelines with UBC 97 Section 1613 +/-.

I'm finding that NBCC loads are higher than UBC 97 loads (?).

Also, when I use the NBCC to calculate pressures from wind velocity, I get higher psf than shown on Table 16-F. That's not so much of a problem as the CpCg factors that I use to get the wind pressures for the design. I get significantly higher loads using NBCC (in the order of 30 to 70% depending on use of end zones etc). NBCC doesn't have exposure zones ....

Can anyone tell me if I'm using the wrong factors to make a direct comparison? It seems that the "specified" loads should be similar (?).

Thor Tandy P.Eng MIStructE
Victoria, BC

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