Wind Speed Comparisons
Wind Speed Comparisons
(OP)
Something that was bugging me at 5pm this afternoon - getting an idea of the differences in wind speeds and wind loads when comparing Australia Vs Europe.
The problem arises in how basic wind velocities are calculated... so attempting to compare basic service winds at 10m height in open terrain...
V50 (1:50) 3 second gust wind in Melbourne is 39 m/s.
V50 (1:50) 10 minute average wind in London is 21.5 m/s.
I understand there are a few different methods to convert/compare these numbers. Is there a basic or conservative factor I can apply to compare them?
When I have time, I'll do a side by side calculation to see if differences come out in the region/shape/area coefficients.
The problem arises in how basic wind velocities are calculated... so attempting to compare basic service winds at 10m height in open terrain...
V50 (1:50) 3 second gust wind in Melbourne is 39 m/s.
V50 (1:50) 10 minute average wind in London is 21.5 m/s.
I understand there are a few different methods to convert/compare these numbers. Is there a basic or conservative factor I can apply to compare them?
When I have time, I'll do a side by side calculation to see if differences come out in the region/shape/area coefficients.






RE: Wind Speed Comparisons
another day in paradise, or is paradise one day closer ?
RE: Wind Speed Comparisons
For example, I'd like to know how to convert a 3 second gust value into a 10 minute average value.
RE: Wind Speed Comparisons
RE: Wind Speed Comparisons
another day in paradise, or is paradise one day closer ?
RE: Wind Speed Comparisons
It can be found in the commentary of ASCE 7, among other places.
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The name is a long story -- just call me Lo.
RE: Wind Speed Comparisons
Edit: Remembered I have a spreadsheet with this conversion formula in it. 3sec:39m/s is 10min:27m/s using the CEM relationship.
RE: Wind Speed Comparisons
I can roughly back up Steve's numbers with V3 = (1.52 / 1.06) * 21.5 = 30.8 m/s.
Therefore London basic pressures are roughly 38% less that of Melbourne.
Example calculation using the Durst Curve below, if anyone is interested.
RE: Wind Speed Comparisons
I've also attached the CEM formula: more convenient than reading from a graph in a lot of cases; and goes beyond 1 hour durations with a supplementary formula. Fairly good agreement with Durst's curve.
Link to image below. I can't figure out how to display it within this post from engineering.com. Any hints appreciated.
Link
RE: Wind Speed Comparisons
From Eng-Tips.com (NOT engineering.com):
Resulting in:
RE: Wind Speed Comparisons
Revised numbers --- LDN pressure = 0.67*MLB or 33% less.
I couldn't edit the post above for some reason.