ASCE 7-16 Clear and Obstructed wind flow

[Mohamed Maher]

Dear All,
Greetings
I design one stadium as shown in the attached.
Photo 1 shows that truss steel column starts from ground.
Photo 2 shows that the steel shed rested on the top of concrete of the stadium.

My questions is it possible to consider the both tents applicable for obstructed wind flow. Kindly advise

In other words how can i calculate the blockage ratio if I consider the end only(nearest point to stadium chairs) its more than 50% if I consider from end of steel shed which is the farthest point than the stadium chairs it will be less than 50 %

Thanks
Mohamed Maher

 

[ProgrammingPE]

Can you try to attach the file again? It has no filename extension so it won't open.

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[Mohamed Maher]

It's a pdf file..l added again in this comment I hope it's work

 

[ProgrammingPE]

I was able to open the file this time, but I had to manually add the .pdf at the end of the filename for it to work.

I'm assuming that you are determining the loads for the design of the steel roof truss. Figure 27.3-4 is for wind blowing into the sloped roof (gamma = 0 or 180), so you need to consider obstructions that block wind when it blows in that direction. Since the seats go from the ground up to a height that is more than 50% of the height of the roof, then I would consider it obstructed.

For wind in the perpendicular direction (gamma = 90 or 270), you'll use Figure 27.3-7. If there's a wall or something below the seats that obstructs the wind, then it looks like you'll be pretty close to the 50% limit, so I would probably design for the worst case for each load case in that direction.

Structural Engineering Software:

http://www.structuralcentral.com

Structural Engineering Videos:

http://www.youtube.com/channel/UCOj2mXXf3ZbZtgxTc6BtkGg

 

[Mohamed Maher]

In case wind 0 and 180 almost till half the canopy , if I talk any section seats doesn't achieve 50 percent closing..or I should take for all the canopy the biggest height for seats from ground and that will be applicable for all te tent and in that case I consider obstructed case .
In Other words if not all the canopy achieve 50 percent what I should do in such a case.