IBC 2012 Wind Loads

[Garfus]

In the new IBC, base wind loads are given on several maps all with the basic criteria of Exposure C. Does anyone have a reference as to converting those values to Exposure D?

 

[DCBII]

I always use ASCE 7 for wind loads (since it's referenced by IBC). The new version (ASCE 7-10) has the following formula for velocity pressure:

qz = 0.00256*Kz*Kzt*Kd*V^2*I

Your Kz factor comes from a table that has different values for each exposure category.

 

[wannabeSE]

The Kz value in equation 16-35 modifies the velocity pressure based on height and exposure.

 

[Garfus]

Thanks Gentlemen.....I got it.

 

[JedClampett]

My understanding of the 2012 IBC, which references ASCE 7-10, is that I has been removed. In it's place, there are site specific wind maps, similar to what they have in seismic. There's a link on the internet that gives you wind speeds for zip codes or longitude and latitude. Unfortunately, I don't have that link with me, but it's great. There are different maps for Category I, II and III/IV structures with the wind speeds for III/IV being more than I or II (duh). The other factors (Kz, Kd, etc.) are pretty much the same.
As DCBII and wannabe said, the tables give the factors for different exposures and heights.

 

[JedClampett]

Here's the link:

http://www.atcouncil.org/windspeed/index.php