[Top] [All Lists]

[Towertalk] Wind info for VE7 - where can I find it?

To: <>
Subject: [Towertalk] Wind info for VE7 - where can I find it?
From: (
Date: Thu, 15 Aug 2002 15:16:43 +0000

Based on the BC Building Code 1998 I found the following 
for your question. Remember the acutal jurisdiction may 
have a different requirement:

The BC code and National Building Code of Canada do not 
use wind velocity. They use a design velocity pressure 
in kPa based on recurrence frequencies of 1 in 10yrs, 1 
in 30yrs, and 1 in 100yrs. The value you seek is the 1 
in 30yr value.

>From Appendix C 1998 BCBC, the values for Vancouver, 
including Richmond, Surrey and W. Vancouver are as 

1 in 10 : 0.36 kPa  = 7.72 psf 
1 in 30 : 0.44 kPa  = 9.19 psf 

You could convert these to mph via p=0.00256*V^2.
Like all codes the design pressure is modified by 
several factors to account for terrain, gusting and 
height above the ground.

The design wind speeds in US codes are based on 
approximately a 1 in 50yr occurance and are based on 
fastest mile velocity for 3 seconds at 30 feet in height.

the B.C. Code formulae is: p=q*Ce*Cg*Cp where:
     q= design velocity pressure
     Ce= exposure factor
     Cg= gust factor
     Cp= pressure coefficient

I will stop now and suggest you get a copy of the B.C. 
Building Code or Xerox the sections you need at the 
library and call the jurisdiction your are in for actual 
local requirements.

Happy calculating

Hank Lonberg, P.E.,S.E.

> Can anybody tell me where to find wind speed info for VE7 or, more 
> particularly, Vancouver?  I may be wrong but I don't believe that I can 
> simply use the value for Seattle.  In any event, from a legal point of 
> view I think it would be hard to defend decisions based on wind data 
> from a different country than the one I live in.
> TIA for your help de Jim Smith    VE7FO
> _______________________________________________
> Self Supporting Towers, Wireless Weather Stations, see web site: 
> Call 888-333-9041 to place your order, mention you saw this ad and take an 
> additional 5 percent off
> any weather station price.
> _______________________________________________
> Towertalk mailing list

<Prev in Thread] Current Thread [Next in Thread>