Wind load on Stacks
Wind load on Stacks
(OP)
Does anybody has expereince on wind load on Stacks (smoke stacks)?
Do they follow AISC7 or there is another standard giving more detailed calculation?
If ASCE 7 methods apply which one?
Any article or document or reference will be greatly appreaciated.
Also would like to know where I can find the deflection limits for the top of the stack.
Thank you for assisting your fellow freshman structural engineer.
Regards.
Do they follow AISC7 or there is another standard giving more detailed calculation?
If ASCE 7 methods apply which one?
Any article or document or reference will be greatly appreaciated.
Also would like to know where I can find the deflection limits for the top of the stack.
Thank you for assisting your fellow freshman structural engineer.
Regards.






RE: Wind load on Stacks
You need to check frequency, etc..
RE: Wind load on Stacks
They were very difficult to design - especially at the opening near the base.
Glad I don't do those anymore.
RE: Wind load on Stacks
DaveAtkins
RE: Wind load on Stacks
RE: Wind load on Stacks
https://www.youtube.com/watch?v=hvg0QQt8Ifk&fe...
BA
RE: Wind load on Stacks
Stacks are so susceptible to vibrations arising from vortex shedding that the "simple" pressures determined in ASCE 7 can be very misleading. When you use STS-1 you'll find a lot of similarities to ASCE 7, with the qz and G (gust factor) calcs being the same, but from there you'll want the vortex shedding-specific coverage of STS-1. You'll find it all but unavoidable to implement some kind of damping to the stack, anything from mass dampers to helical strakes and/or bearing pads.
ASCE 7 - C26.9, "The gust effect factor accounts for the loading effects in the along-wind direction due to wind turbulence-structure interaction... It does not include allowances for across-wind loading effects, vortex shedding, instability due to galloping or flutter... For structures susceptible to loading effects that are not accounted for in the gust effect factor, information should be obtained from recognized literature."
The last stack I had my hands on I did a quick analysis without any damping measures on the stack:
Overturning moment from ASCE 7 wind (inline with the direction of the wind) = 330 k-ft
Overturning moment from STS-1 wind (perpendicular to the direction of the wind, from vortex shedding) = 1150 k-ft
Also, with vibrations from vortex shedding you'll need to evaluate fatigue... Have fun!
RE: Wind load on Stacks
If you are a freshman engineer, you really should be getting some assistance from your boss in determining design loads. It is not an area familiar to the average structural engineer. If you are not sure, seek assistance from someone experienced in this type of design either inside or outside your firm.
BA
RE: Wind load on Stacks
What's the full name of STS-1? Where I can find a copy of that?
I thought for all stacks you do a tunnel analysis? Is STS-1 a tunnel analysis?
I apprecaite for your vast knowledge and information. I like to learn it but my hands are tied.
Thank you
RE: Wind load on Stacks
Great links from BAretired. Take his warning seriously (in fact, always take BA's advice seriously) - this subject just isn't as straightforward as a cantilevered beam in a building structure, even though it looks like it from a first glance. I applaud you if you want to dive into this, but you'll need substantial oversight, assistance and collaboration from a senior engineer in the long run.
Wind tunnel testing isn't required as far as I know, but wind tunnel testing will usually result in lower design forces/pressures. The problem is getting a client to commit to the design cost and schedule associated with wind tunnel testing.
ASME STS-1 Steel Stacks
latest edition is 2011
Here is the cover page and table of contents:
Cover Page & Table of Contents
Here is the page where you can order a copy:
ASME Product Page for STS-1
You may be able to find a PDF of the old 2006 edition floating around on the web somewhere...
RE: Wind load on Stacks