enclosure classification

huangyhg

enclosure classification
i have a very large dairy farm that i am designing.  it's 100' wide with 14' tall sidewalls and is more than 1/4 mile long.  it's a simple, very large rectangle with a 3.5/12 roof pitch.  the endwalls are closed with a few overhead doors.  the sidwalls are completely open, with the exception of adjustable curtains.  
i'm struggling how to determine the classification of this building.  in the wind direction perp to the ridge, i have open walls with curtains on them.  realistically, if the curtains were up, they would blow off before we got anywhere near the design wind speed.  if they were down, the building is very "open" in that wind direction.  
1)  can i call this an "open" structure?
2)  can i call it "open" for wind in one direction and maybe "partially enclosed" for wind acting parallel with the ridge?
i'm curious how the rest of you would classify this building.
thanks.
i would probably say it is open for all directions, as i do not think internal pressure could develop given the open sides, regardless of wind direction.   
but are you also asking if you can assume for design perpendicular to the ridge that the curtains are gone (wind load only on the roof)?  i would not do that.
daveatkins
thanks guys,
i'm not suggesting that i'm only going to design for pressures on the roof.  i am going to assume that for mwfrs loads in all directions that the curtains remain on the building.  however, for my internal pressure coefficients, i'm going to assume they're zero to prevent unneccessarily conservative uplift and/or c & c loads.