Uplift on Fence panels 1

[Hamza Bubtana]

Hello Everyone

I am struggling to work out how to calculate the vertical uplift (not the normal wind force) that the wind would produce on a fence panel. A client is worrying it will be lifted out of the web of the post as it is not secure just placed. andy ideas on how to calculate uplift on vertical surfaces like fence panels.

Best regards

Hamza

 

[raligt]

How thick is the fence? Wind uplift will have a negligible effect on the fence compared to the overturning generated from horizontal wind.

 

[Hamza Bubtana]

Hello Raligt

The fence is an acoustic barrier that is 150mm thick and has a 300mm capping placed centrally to the panel.

I know its a small amount but the client is asking for proof it's not a factor so I need to be able to at least estimate it.

Best regards

Hamza

 

[raligt]

You could adopt a pressure coefficient of wind loading to a canopy roof, to Eurocode, this is Clause 7.3, EN 1991-1-4.

May be quite similar to your situation.

 

[Hamza Bubtana]

Thanks for your help Raligt

Yes, that might work for the capping.

For the fence itself, I was looking at using Frictional forces using EN 1991-1-4 clause 5.3 (3) and cluse 7.5

What are your thoughts?

 

[raligt]

I would agree. I believe that your net wind will be quite low, and uplift won't be an issue but to satisfy the Client, I think this would be your best route.

 

[dhengr]

Hamza Bubtana:
Sometimes, as an engineer, you have to come up with a nice/polite way of explaining to a client just how absurd and foolish their question or request is. You usually want to frame this explanation at about a 6th to 9th grade physics and engineering mechanics level so that the general public, a jury, an attorney will understand it. That is about the level that the general public’s and jury’s eyes start glazing over when you are explaining tech./engineering matters. What are the primary/most important design loads, and how have to handled them? Look at the small percentage of these real loads which the up-lift could be, assuming you could come up with an accurate up-lift per foot of fence. Explain why up-lift is caused by wind, on roofs and the like, but is less critical on a smaller structure, like a fence. You can sometimes even do fairly simple experiments or tests to show the general principle or range of possibilities. These kinds of questions are seldom answered satisfactorily with some trumped-up calculation using a bunch of unknown variables, although they do, at times, seem to satisfy the uninformed. Get a price on some wind tunnel testing and present that to him. Then, ask if he still wants you to report on the matter, and pay the testing price. Some things are just so stupid that even the code writers haven’t gotten around to codifying them or tabulating design coefficients, yet.

 

[Whoopdedo_LSU]

I would consider a prying affect(overturning). reference applicable codes to determine this affect.