Wind load force coefficient on a light bulb of a 10m high light pole (ASCE 7-16) 2

[Fleabagger]

Hi all!
I am designing a foundation for a light pole whose diameter at the bottom is 205mm and 114mm at the top. The pole section is tubular of 5mm thickness and the light pole is 10m high. The lights are 500mm x 430mm. I would like to know the force coefficient I should use in the estimation of wind load on the light bulbs. Would it still remain 1.8/2 which is usually the Cf of a rectangular section? Or is there any clause in ASCE which lets us bypass this rule thereby allowing us to estimate the wind load using a smaller value of Cf?
Thanks!

 

[Lomarandil]

I'm usually all for sharpening the pencil, but even I'd be reluctant to try to get lower than Cf=2 for attachments to a light pole (unless you somehow have wind tunnel testing data from the manufacturer, and are confident that the installed configuration will match).

If that really makes a difference in your foundation design(!), you are probably flying too close to the sun.

 

[fel3]

Have you looked at ASCE 72-21, "Design of Steel Lighting System Support Pole Structures"? If not, then I suggest you get a copy because it provides detailed information and guidance for this type of design that ASCE 7 does not.

BTW, ASCE 72-21 is referenced in ASCE 7-22 several times. I don't have ASCE 7-16 to check if an earlier version of ASCE 72 is referenced there (ASCE 7-10 does not reference ASCE 72 at all).

ASCE 72-21, §2.7 Wind Load is the place to start. Table 2-1 has wind directionality factors for two conditions. Table 2-2 has drag coefficients for pole structures for 21 conditions. Table 2-3 has reduced drag coefficients for multi-sided poles with rounded corners (10 conditions, but only 5 are actual reductions). Table 2-4 has drag coefficients for "General Appurtenances" (9 conditions), which would include the luminaires.