Wind loading calculations

Has anyone ever had to do wind loading calculations on a model? I have
a product that is designed to go on the top of a lamp post and the
client wants to know the wind loading calculations.

Not a clue where to start!

 

You might find some of these useful:

http://www.mecaenterprises.com/downloads.htm

Andy Graham skrev:

 

It certainly is something that is quite involved when you start doing a
bit of Google work on it.

The product is a CCTV unit that goes on the top of a lighting column
(or specialised column) and the customer is looking at getting some
figures as to the kind of additional loading they will need to provide
for by having the unit up there. They have a wide range of lighting
columns available to them so I would always advocate the bigger the
better as "whip" will always be a factor with a moving unit.

In my ignorance I assumed there would be a standard formula along the
lines of surface area x wind velocity = magic answer. From what I have
read the other factors of air pressure etc play a massive part in the
calculations.

I am in the UK and regards to your comment about getting a structural
engineer to sign it off - I wish! Sadly from what I can gather so far
if the engineer wanted a fiver for his time the client would run
screaming.

 

The standard codes that a building structural engineer will look at
are not really designed to help with something as small as a CCTV
camera. You will be able to get a feel for the direct pressure
loading due to windspeed. The web will give you average windspeeds at
differnt heights in different parts of the UK - I'll have to see if I
can relocate the link. I doubt the second order effects are really
worth bothering but that sort of assumtion is how things go wrong !!
Try CCTV camera suppliers an see if they have any recommended
fasteners and brackets for different locations.

If you client makes lighting columns, don't they have the inhouse
expertise to appraise the wind loading of various lamp housings on
the top of their posts? A CCTV housing would be similar - I think.


Jonathan

 

You can try ANSI/TIA/EIA 222 standard. That is the standard that governs
towers and antenna poles. The calculation method in there is taken from an
ASCE book that has a lot of wind loading information.

 

As someone mentioned above, the best place may be to go to the camera
manufacturer and tell them that you need the wind load rating
capability. If the laws in the UK is anything like the US this means
that the Manufacturer is the one that is ultimately responsible.
Actually this makes more sense because the engineerin for the camera's
can be spread out of a large number of camera's. A Structural
Engineering Analysis here in the States is more for custom, one of a
kind and unique situations not something that comes out of a box. In
the States the UL sticker on the camera would not apply but the
European standard takes in a lot more of the physical issues of
products and if the camera is properly rated then this work could
already be done.

One other comment is that someone mentioned the average wind load.
What is really needed is the maximum wind load that has been accepted
by the appropriate regulatory agency.

Assuming that the product is properly rated then a good assumption is
that if the mounting holes that are provided with the camera are all
utilized, (ie. proper size and number of fasteners) in an appropriate
manner then this should be good.

Now, as a rule of thumb I have been told that here in the states that
the structure should be able to withstand 50 pounds per sq foot.
Again, this is only a rule of thumb and a smaller item would have less
"effective" area then a flat wall but it is unlikely that the camera
has more then 1 sq foot of area, (unless it is a massive camera and
housing) and it is hard to imagine that standard mountings etc. would
not be able to handle 50 pounds. So, there is a good chance that this
is a very low probablility of failure but the camera manufacturer
should definately certify their product. If not then you should find a
different manufacturer.

Hope this helps.

Ed


Hope this helps



It is also fairly safe to assume that if the camera comes with