Wind Response Sectrum 2

[jheidt2543]

Are wind response spectrums available, similar to seismic response spectrums, and if so from whom and in what form?
This question came up on a project in the last few days and I'm wondering if anyone has looked into this.

I am checking the design of a 60' tall sculpture to be placed in a non-seismic area. I am wondering what effect gusting wind might have on the structure vs. just a static wind load.

 

[ERV]

In seismic analysis, response spectrum is the curve showing a relationship between the maximum response and the frequency or period of a structure. The responses can be displaced, velocity, and acceleration, in which case the corresponding response spectra are called displacement spectrum, velocity spectrum, and acceleration spectrum, respectively. It is convenient to show all three responses together in one figure called tripartite response spectrum.

In wind analysis of rigid structures frequency of the structure is negligible and is not considered in the analysis.

In flexible structures (such as signs) frequency of the structure must be considered and the Gust Effect Factor (Gf) is taken as 0.925 as opposed to (G) 0.85 for rigid structures. See section 6.5.8 in ASCE 7-98 or 7-02.

In conclusion, plotting gust effect (structure response) of flexible structures is possible and has been done for certain dynamically sensitive structures. I will check to see if I have any papers relevant to this type of analysis.

One important consideration for three sided, spherical and other odd shaped structures is vortex shedding. Typically structures such as the one you have described should be carefully analyzed and nothing overlooked, check and double check.

 

[ERV]

jheidt2543,

Here are a couple of links that may be of interest:

http://www.nd.edu/~nathaz/database/main.html

http://www.nd.edu/~nathaz/research/zhou/ind988.pdf

 

[Tbilly]

Can anyone direct me to info relating to IBC 2003 1609.6.1.1 item 3? Vortex shedding etc.