Measuring wind load

[dr pepper]

I want to measure wind load on a tent, not the camping kind, and industrial warehouse tent 20 x 40 meters.

I was thinking of just having a square of ally or whatever attached to a load cell as a sort of 'flag', measure the force applied to the load cell via the flag and just scale this up as a ratio, the area of the flag to the area of the side of the tent.
The tent is protected on 3 sides so just the one side needs measuring.
Would this work?, or would I be better chasing my original idea of using an anemometer.

 

[alec_t]

If the tent has guy ropes, perhaps spring balances could be used to measure changes in tension in a few of the ropes?

 

[dr pepper]

No it doesnt, its frame is bolted into the concrete.
There is an optional storm guy rope point at the apex however this would be anchored right in the middle of where lorries turn round, so its only going to be put in when it svery windy.

 

[dknguyen]

I want to measure wind load on a tent, not the camping kind, and industrial warehouse tent 20 x 40 meters.

I was thinking of just having a square of ally or whatever attached to a load cell as a sort of 'flag', measure the force applied to the load cell via the flag and just scale this up as a ratio, the area of the flag to the area of the side of the tent.
The tent is protected on 3 sides so just the one side needs measuring.
Would this work?, or would I be better chasing my original idea of using an anemometer.

I don't suppose you could connect a tensioned cable to some wall opposite of the entrance with a force meter somewhere along the cable? Maybe even connecting the cable to somewhere on the frame might work. Then zero the force meter when there's no wind. The cable probably can't be placed perpeindcular to the tent wall but then you can just run the force reading through some trig.

But with the force sampling method, would it just be dependent on the surface area? I'm sure the size of the entrance plays a role too. I kind of wonder how well it would work if instead of an aluminum sheet, you used a little enclosure with an entrance cut out of one side so that the ratios of dimensions are all a mock-up of the tent.

 

[alec_t]

I was thinking of just having a square of ally or whatever attached to a load cell as a sort of 'flag', measure the force applied to the load cell via the flag and just scale this up as a ratio, the area of the flag to the area of the side of the tent.

That would be ok if the wind speed were the same over the whole windward wall. In practice, wind speed will be lower at ground level than at tent ridge level, and wind turbulence will give an unpredictable pressure distribution. So you would probably need to monitor forces at various points across the wall.

Edit: If the tent has a (semi-)rigid framework it should be possible to measure distortions of the framework to indicate wind-load.

 

[Tony Stewart]

Estimate from this calc. https://www.engineeringtoolbox.com/wind-load-d_1775.html

 

[Pommie]

Can I ask, why you want to measure it?

Mike.

 

[dr pepper]

Of course you can.
The guy rope blocks a part of the Hgv trailer park, so the rope only wants to be in place when its windy.
I have a spec that tells me what is too windy and the rope is needed.

Nifty calc that Mr Stewart, I think I'm going to go with a hot wire anemometer, a mechnical whizy thing is just going to fall apart after a while.
Fiddling with the calc temp seems to make a big difference on air density which makes a big difference on load, so I'd need to measure temp and also take it into account.

Tell you what at 30mph which is considered a brisk day here makes over a 1/2 ton of force on a 50m2 wall.