NOAA to ASCE 7

[LPPE]

I have a job where the wind load requirement is to use the NOAA Category III Hurricane wind speed of 130mph converted to ASCE 7-10 basic wind speed for structural design

This is fairly simple in this case, Table C26.5-2 in ASCE 7-10 gives the approximate relationship between NOAA and ASCE 7. Luckily, 130mph is the maximum wind speed of Category III, so using that table, the maximum ASCE 7 3 second gust over land is 143mph.

Now my job specification gets a little cloudy - it says "The foregoing wind value does NOT include an increase for basic wind speed figures. Accordingly, the 3 second gust wind shall be multiplied by a conversion factor to simulate inclusion of the increase with basic wind speeds for use with ASCE 7-10. Refer to the Table for Design Wind Speeds from ASCE 7-93 to ASCE 7-10. In the 2010 edition of ASCE Standard No. 7, this is Table C26.5-6."

All Table C26.5-6 is telling me is that wind speeds from ASCE 7-05 to ASCE 7-10 are multiplied by sq.rt of 1.6.

I'm trying to figure out what they mean by "a conversion factor". I don't believe they're talking about the wind importance factor.

Anyone have any suggestions?

Thanks

 

[LPPE]

I do have a Risk Category III and IV Building, so maybe that is the conversion factor I'm looking for. The 143mph maybe is only for a Risk Category II Building?

 

[SlideRuleEra]

Plot the location of the project on a map. Perform the design per ASCE 7-10 for that location, thereby avoiding any confusing conversion factors.

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[JedClampett]

If you multiply your 143 mph by the square root of 1.6, you get 181 mph. From my experience, that's a typical windspeed for a hurricane zone in all but the absolute worst Florida areas (Keys, Miami Dade County, etc.) for a Risk Category III/IV building. The importance factor is built into the windspeed.
So I think you're on the right path.

 

[JedClampett]

Or as SlideRuleEra says, use

http://windspeed.atcouncil.org/.

Best website ever.