Wind force to velocity
Wind force to velocity
(OP)
Can anyone give me a few pointers.If i had a wind force acting on wall of given dimensions (say 3m h x 4m w), how easy is it to calculate the wind velocity?
When was the last time you drove down the highway without seeing a commercial truck hauling goods?
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RE: Wind force to velocity
q air = 1.2kg/m^3
F = force per unit area
v = wind speed m/s
Also
F =p*A
p = wind pressure
A = area
hope this helps!
RE: Wind force to velocity
pressure = 1/2*rho*v^2
rho = 0.00238
v in ft/sec
A in ft^2
Force in lbs
RE: Wind force to velocity
hopefully I haven't confussed!
RE: Wind force to velocity
RE: Wind force to velocity
There are several issues to consider. The two formulas above are for stagnation pressure, and will not necessarily give you the net force on a rectangular surface. The factors suggested by UcfSE would be used to get from a mapped wind velocity as specified by ASCE 7 or similar source to the design loading on a surface. But the building codes aren't set up to be worked in reverse, and I'm not sure how meaningful the results would be when you do this. Probably the best you could do is to state that per a given building code, the structure should have been adequate for a specific wind speed.
RE: Wind force to velocity
RE: Wind force to velocity
RE: Wind force to velocity
The formulas presented by Nicam and rb1957 have to be multiplied by the pressure coefficent appropriate for the structure in question to be able to calculate the force on that structure.
The pressure coefficients found in codes would be safe averages, but probably not accurate enough for the reverse calculation suggested.
RE: Wind force to velocity
RE: Wind force to velocity
RE: Wind force to velocity
I do agree that the other factors such as directionality factor, importance factor, topographic factor etc are not required.
RE: Wind force to velocity
RE: Wind force to velocity
Using this approach will give you a specific velocity. Velocity should actually vary from zero at the ground and increase with height, so you're finding some sort of average velocity, not the velocity at the top of the wall. The building codes are based on 3-second gust at 10m height, which doesn't mean the actual velocity is equal to that at any point on the sign.
RE: Wind force to velocity
RE: Wind force to velocity