ASCE 7-10 Wind Loads 2

[SteelPE]

What was the purpose of switching the wind provisions from ASCE7-05 from allowable to strength methods in ASCE 7-10? IBC requires you to calculate wind loads in accordance with ASCE 7-10 but then requires you to calculate a Vasd?????? and Vasd is the determining factor when you get into the Structural Observations for Wind Requirements of chapter 17. Not to mention that now all of my allowable wind drift and deflection limits (H/400 under allowable loads ect.) are all different because of the increase in the wind speed.

Very frustrating.

 

[JedClampett]

It's kind of a book-keeping problem. We design multi-structure water or wastewater treatment plants. On the structural general notes, we used to put the design wind speed. We also have to put the design wind speed in the specifications for the electrical and mechanical equipment suppliers to use. Some of the buildings have different Design Categories (some are storage only, some have hazardous chemicals in them, etc.), so we might have Category II, III or IV on the same project. Now instead of one working level wind load and assigning Importance Factors, technically we need to give different wind speeds for each structure. Add to that the fact that the suppliers need to adjust the wind loads by the .6 load factor is just something else to add to the confusion.
I actually don't mind the whole concept and having site unique site specific wind speeds is pretty awesome. And it's not any harder to use than ASCE 7-05. I just have a problem with the fact that just because we have bigger computers that we need to add several layers of complications to the code that was OK. I'm carrying wind pressures to three figures for pity's sake. Does the wind know that?

 

[Archie264]

>>>I'm carrying wind pressures to three figures for pity's sake. Does the wind know that? <<<

It must. It seems to know what category the building is.

 

[DST148]

@Bookowski> Thanks for the info about simplified wind pressures still being used in NYC.