>
> Interesting, using letters for exposure classification. I guess you
> cannot interpolate between classifications and multipliers, or start
> with roughness length (z0) and side of a hill or escarpment. So
> AS1170.2 is fine for wind flowing off the Adelaide plains up the
> Adelaide Hills, but not realistic within the hills themselves.
>
>
>
> How does ASCE7-05 treat topography?
>
>
>
ASCE 7-05 defines a roughness length parameter, z0, in the Commentary to
Chapter 6 (Wind loads) on page 287. The typical values and ranges for
each exposure category is given in Table C6-8 on page 319. The formula
for z0 is:
z0 = 0.5*Hob*Sob/Aob where
Hob = average height of the roughness in the upwind terrain
Sob = average vertical frontal area per obstruction
A0b = average area of ground occupied by each obstruction
I find it easier to look at the photos in the Commentary that are
representative for the exposures or use C if in doubt and I know I'm not
near water.
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