ASCE 7 Wind Speeds 180MPH 1

[Gumpmaster]

I'm working on a location that has a wind speed (3 sec gust) of 180 MPH!!! The ASCE 7-05 simplified wind tables only go up to 170 MPH. I don't really want to go through the full blown wind calcs (simplified method is much easier).

Has anyone ever run into this? Is there a method to upconvert the wind speed for use in the simplified method? Thanks.

 

[JKStruct]

I don't know of a way to "upconvert" the wind pressure. Extrapolating from the tables would get challenged by any reviewer, in my opinion.

My office has a vendetta against Method 1 of ASCE 7. And, I agree. Method 2 is not much more complicated; it's more accurate; and it won't take too much time once you get used to it. It's good practice, and I think it's quite fun actually.

Viva Method 2.

 

[SteelMover]

(180^2/170^2) will get you pretty darn close but I wouldn't reccommend trying that with your basic wind speed. Method 2 also has its limitations based on structure geometry. Read the commentary.

I use that conversion occaisionally for a fast check, to make sure my #'s look correct

 

[JKStruct]

Method 1 has many limitations as well.

Send the building to wind tunnel. Follow up with an apology letter to owner. Assure him in the letter that the building will be designed better than method 1.

 

[UcfSE]

If you're alrady into a 180mph zone, it wouldn't be good to "cheapen out" by doing a lot of work to get out of doing a lot of work just to get an answer that isn't as accurate. Just do it the right way with the analytical method.

 

[csd72]

Steelmover Had the right idea, check out the formula for basic pressure you will find that the only variable that changes is the wind speed therefore you need to up the pressures by(180/170)^2.

I would, however recommend that you use the longer method in this case as this would be more legally justifyable.

 

[Ron]

180 mph wind zone is no place to play with extrapolated "simplified" method...use the analytical method or wind tunnel.