On Fri, 10 Oct 2003 09:57:38 +0100, Christopher Norton
wrote:

The message
from (Nick Maclaren) contains these words:


In the booklet "The Design of Free-standing Walls", there is a map
showing the speeds that are used for building design in the UK. I
am not going to summarise it (as it is very complex), but here are
a few examples:

London 37

that may not look much, but it is in fact Force 12 75 MPH

It doesn't give much reserve for really big storms.

It's not surprising that roof get blown off.

Colchester 41
King's Lynn 44
Newcastle 46
Truro 48
Edinburgh 50
Glasgow 52
Lewis 55

All are in metres/sec, and remember that wind damage is roughly
quadratic in the speed. There is also a varying factor due to the
openness of the terrain.


Regards,
Nick Maclaren.

Plus of course it gets really interesting when you add it up with 3
other walls to get a basic box. You get suction and all sorts of forces.
Then if you add a pitched roof you have the possibility of wind uplift
on the roof pulling the roof off along with the walls!!!!!!!!!!

plus the potential accelerating effect of buildings up wind.

Try walking past York Minster on a really windy day.
--
Martin