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Flagpole Wind Loads

Flagpole Wind Loads

Flagpole Wind Loads

Does anyone know of any codes or standards for use in determining the wind loads on a flag pole?  I would imagine the flag would contribute to a fair bit of drag and increase the moment on the pole.

RE: Flagpole Wind Loads

I think to remember the Spanish code says use 25% of its surface as if orthogonal to the wind. Im verify, yes, it is so, specifically,

"En las banderas sueltas se computará el 25 por 100 del área de la tela."

It is surmised the flag is left to drift free. If not the whole area may be required.

RE: Flagpole Wind Loads

National Association of Architectural Metal Manufacturers -
NAAMM - Metal Flagpole Manual plus Guide Spec. for Design Loads on Metal Flag Poles should give you all the information you need.

For ordering, their fax no. is  312/580-0165
                    tel.no. is  312/456-5590

RE: Flagpole Wind Loads

Australian Standard AS 1170.2:2002 Structural design actions: Wind actions, Appendix F, has a treatment for calculating the aerodynamic shape factor for free flags, which includes the dynamic effects from flutter.

C = 0.05 + [0.7 * m/(p*c) * (A/c^2)^-1.25]

- m is the unit mass of the flag (kg/m^2)
- q is the density of air (nominally 1.2 kg/m^3)
- c is the height of the flag (m) {Note this is not height above ground of flag but actual height of flag}
- A is the area of flag perpendicular to wind direction (m^2)

RE: Flagpole Wind Loads

The UBC specifically covers it in chapter 16.

RE: Flagpole Wind Loads

Analyze this!  I bought a flagpole for MIL for Christmas.  They said put 10% of the length in the ground in a hole the same dimension in width and fill with concrete (cuz that's what the directions say). I bought a 20 foot pole with a 3'x5' flag, so I'm using a 2'diameter by 2' deep hole with concrete.  Is that scientific enough!!

(since it's on a windy hill, I think I'll add another foot of depth with some reinforcing.  also lining the inside of the pole with driveway sealer and filling with concrete and a bar!  very thin aluminum pipe for $100)

PS: BTW, for light poles, the rule of thumb is 20% of pole height in the ground and is usually conservative (no rule of thumb on diameter though)

RE: Flagpole Wind Loads


I have a design aid for determing the depth of pole foundations.  I dopnt remember where I got it.  

The depth of the pole is related to the pole diameter, soil pressure, and height to the flag.  

If you are intersted, e-mail me at CSELLC@optonline.net and I'll send you the PDF of it.

RE: Flagpole Wind Loads


I sure would appreciate a copy of your pdf on the pole foundations.  Please send to jheidt2543@aol.com .

Thanks in advance!

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