Wind Corner zones on multilevel buildings with differing outer extents 1

[Revv]

Hey Guys,

So when figuring out my zone 5's for my building, how does it work if for example, my 2nd floor extent ends before my 1st floor extent. Do I still go the same amount inward? So if my "a" is 15', do I go 15' from the exterior extent of the first and 2nd floor even though the 1st floor juts out further?

Thank you!

 

[phamENG]

Generally speaking, I would say yes. It's best to consider why those zones exist and, when you have a non-conforming structure and no budget for a wind tunnel test, look for places where the condition will occur.

Do you understand the why of the higher load edge zones?

 

[jjl317]

Just to ensure we are on the same page, you are referring to ASCE 7, components and cladding wind pressures?

If so, I am unaware of any clear guidance on this issue within ASCE 7, though I wonder if it might be covered somewhere one of the new wind load guidebooks (by Coubourne or others), but I haven't purchased any recent versions of these. Not sure if anyone who might have access to these can chime in?

Typically, I have based the corner zone width "a" based on the widest least building width, and used on every floor, regardless if the footprint got narrower on subsequent floors. Might be somewhat conservative, but I feel that the wind load criteria in ASCE 7 can be pretty arbitrary anyway.

And not sure which version of ASCE 7 you are working from, but the commentary of ASCE 7-16 has some additional clarifications on corner zone widths at building offsets and non 90 degree corners that are definitely a help (and were long overdue)

Hope this helps

 

[Tomfh]

It's best to consider why those zones exist

Do you have any good references on it? I’ve always wanted to see the data behind those pressures zones.

 

[phamENG]

I was speaking more generally about aerodynamic effects, but I'm pretty sure I have some deeper technical documents on it somewhere. I'll see if I can find them.