Fundamental frequency of a single-pole sign structure 1

[epr]

In order to determine wind loads using ASCE 7, there seems to be adequate information available regarding fundamental frequency and damping ratios for flexible buildings.

However, in researching, I have not been able to find a good reference for calculating these factors, nor a table or chart referencing suggested values for single-pole sign structures.

Can anyone point me in the right direction?

 

[ERV]

Force on Components and Cladding
ASCE 7-98, Equation 6-20; F=qz*G*Cf*Af

The values of qz (velocity pressure evaluated at height z of the centroid area of Af) are the same as MWFRS except the value of G = 0.85. The design forces can be determined using appropriate Cf (net force coefficients from tables 6-9 through 6-12) and Af (area normal to wind) for each component.

tip: divide your sign into height increments such as 0 to 30 ft, 31 to 60 ft., etc., to find total load.

Guide To The Use of The Wind Load Provisions of ASCE 7-98 (also available for 7-02) published by ASCE is an excellent reference for wind load calculations.

 

[epr]

Thanks ERV.

However, for designing the main sign structure (pole and foundation), it is not considered components and cladding, and "G" must be determined based upon a flexible or rigid structure (per Section 6.5.8).

Thus, my original question re: where can I find a good source for fundamental frequency and damping ratio, for single pole sign structures.

 

[ERV]

Correct. If the structure has a fundamental frequency less than 1 Hz. it is considered a flexible structure, and the gust factor G = Gf, will be calculated per 6.5.8.2 Flexible or Dynamaically Sensitive Structures (ASCE 7-98). Gf = 0.925 (Equation 6-6).

Try this link:

http://www.geocities.com/lpittack/cae614proj.html

 

[ERV]

This will be a big help for anyone needing engineering for signs:

http://www.iccsafe.org/e/prodshow.html?prodid=106H98&stateInfo=PisldhyjilkYlShm7360|3

 

[epr]

Thank you ERV.
You have been most helpful. And thanks for the quick response.