×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Wind Loads on a flagpole??

Wind Loads on a flagpole??

Wind Loads on a flagpole??

(OP)
I do not see any reference to this in either AASHTO LTS-4, 2001 or ASCE-7, 98.  Given F=0.00256*Kz*Kh*I*Cd*(V)^2*A, what would you use for the Cd?  All other coefficients are easy to calculate.  Is this the correct methodology?

RE: Wind Loads on a flagpole??

See ANSI/NAAMM FP1001-97 Guide Specifications for Metal Flagpoles.

RE: Wind Loads on a flagpole??

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]

Where:
- 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: Wind Loads on a flagpole??

dbuzz,
Is A just the flag area? With the wind blow, the flag will be in the wind direction and vibrate.

RE: Wind Loads on a flagpole??

civilgee,

Cd is the drag coefficient for a cylinder; roughly 1.0 max for high wind speeds (> 100 mph), assuming a 6" diameter; and it won't change much at higher speeds or at diameters within .5x to 2x of that.  Most good fluid dynamics textbooks will give a plot of the Cd of a cylinder for various Reynold's numbers.

RE: Wind Loads on a flagpole??

(OP)
I appreciate the help.  I will order the NAAMM FP 1001-97 standard and see if that helps.  As far as the wind load on the pole I have that under control....it is just how to determine the loads from a flag that is flapping.  Thanks again.

RE: Wind Loads on a flagpole??

This may be an oversimplification, but why not call a flag manufacturer, give them the size of the flag and pole and where it is to be located and have them provide the foundation loads?

RE: Wind Loads on a flagpole??

If you are accustomed to the ASCE 7 code, chances are this would be classified as a flexible structure with a frequency less than 1Hz.  It is also a round pole.  If you follow the code closely, there are specific methods for calculating the wind pressure for these types of structures.  Reference ASCE 7-95 for some background information first.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources