NV65 and TIA 222-G

[hassaning]

Hello!
I have a question about results that I found!
I calculated velocity pressure and strenght due to wind with french standard NV65 and with americain standard TIA 222-G and I found an important difference about 40% !!! Please can you tell me if my results are logic?

 

[JoshPlumSE]

I'm not familiar with the NV65 code. But, am quite familiar with TIA. My guess is one of a couple of things:

1) Did you use the same wind speed for both codes. I know that the TIA-G standard is based on a 3 second gust wind speed. If you use that with any other wind designation, then you would get different results than intended by code. If NV and TIA do not use the same wind standard, then you would have to start out using different wind speeds.

2) The steel code from TIA is an ultimate strength or limit states based steel code. It expects you to take the results from your wind pressures / forces and then mulitply them by 1.6 then compare this to your strength limit states. If the NV code is an allowable stress based code or if it using different load factors on wind, then a direct comparison may not be apples to apples.

 

[hassaning]

Thank you for your response!
I have two speed: normal=120km/h and extreme=150km/h.
In attachement file you'll find method and results!

 

[hassaning]

Sorry is not the true file! here is the true!!

 

[JoshPlumSE]

My point is that you may not be able to use the same wind speed for both codes. The best example I can think of is the TIA G standard vs the TIA F standard.

The G standard is based on a 3 second gust wind speed. Typical wind speeds for California (where I live) are about 85 miles per hour.

If I pull up the F standard (which is based on a "fastest mile" wind speed) then the typical wind speed in California would be approximately 70 miles per hour.

If I used a fastest mile wind speed in a case where I should have used a 3 second gust wind speed, then I'd probably get a force value that was about 40% off from what it would have been if I had used the correct wind speed.

Therefore, the important thing is to make sure that basis for the design wind speed you are using matches the code you are using.

 

[hassaning]

Thank you!
I think for the TIA-G standard we must use 3 second gust wind speed which is normally given in the specifications of the client, but for the NV65 standard we must rely on the operational wind speed (120km/h in our case) also given by the client!
I calculate with this parameters and I get about 12% off.
The question now is: this standard is really optimized? it can happen to reduce the strength of this value?