How to define wind coefficient for walls in open buildings?

[tmgczb]

For open buildings，with wall in only one side of the building，coefficients of wind pressure are given for roof in ASCE 7-05/10/16.
But coefficients for wall in such buildings is not mentioned in ASCE or maybe was ignored by me.
I consider we could take it as a freestanding wall.
I want to hear your experience. Any idea is helpful.

 

[tmgczb]

Waiting for anwsers and suggestions.

 

[hotmailbox]

I posted a similar question here a short while ago without an answer. My case is at the corner with 2 walls. I ended up estimating the wind on the walls as freestanding (ignoring the roof) and the wind on the roof as open structure with blocked wind flow.

 

[tmgczb]

@hotmailbox
Thank you for shearing your experience with me.
I agree with you except that I'm not sure if obstructed wind shall be used for roof.

 

[hotmailbox]

if obstructed wind shall be used for roof.

Shouldn't it be used for wind perpendicular to the wall?

 

[tmgczb]

Why not clear wind flow or whichever is more critical?

 

[hotmailbox]

I consider both wind directions.

 

[tmgczb]

For both wind directions, you consider obstructed wind flow?

 

[phamENG]

In this case obstructed will give you the worst case. It'll be your highest pressure on the wall, and the highest uplift pressure on the roof. That will result in the largest bending moment on your base - looks like this is a cantilevered set-up, sort of like a little bus stop?

I would use obstructed for all directions but exactly parallel to the wall.

 

[tmgczb]

Thank you very much. I understood your idea.
For wind parallel to wall ,is there a horizontal drag force defined in ASCE?
For this case, wind on roof varies according to distance from windward edge. But for walls in this case, nothing is mentioned.

 

[phamENG]

No, there isn't. The loads are generally considered to be conservative, so if you run the loads for all directions of applied wind you'll capture "enough" to design a structure that will resist the wind loads. Of course that isn't always the case, and you have to use your judgement. If you feel that consideration of horizontal drag is important, you can always go back to a 1st principles fluid dynamics analysis and compare the results to ASCE's wind calcs.

 

[tmgczb]

My friend, in your model, do you consider 2 adjacent walls as freestanding walls？