guyed stack design

huangyhg

guyed stack design
is there a 'standard' for the design of guyed stacks published by some organization?  i am familar with wind pressures (25-33 lbs/sqft - 100mph) and wind loads (pressure x projeted area).  i am less familar with accepted methods of calculating critical buckling loads, determining gauge thickness, effect of stiffeners, number of guys, etc.  are there inexpensive programs that use the equations of this 'standard' and my design requirements (height, diameter, wind speed, etc.) to select the minimum steel gage, number of guys, etc.  i would appreciate any information.  thanks harvey13
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i have been designing guy wire supported stacks for many years and i am not aware of any published standards that are available.  there are some text books that address guy wire supported stacks a little, but they are usually not real helpful.  you mentioned wind loading, and you should be aware that guyed stacks are flexible structures and the wind loads can be significantly higher than that on non-flexible structures.
i have several programs related to stack design on my web site at
harvey13:
first of all, you need to get a copy of asce 7-95, minimum deaign loads for buildings and other structures.
just knowing the conversion from mph to psf pressure is only a small part of the problem.  
in addition to basic pressure, you will need to account for height, gust, shape and terrain factors.  the gust factor is affected by the shape and natural frequency of the structure.  if the frequency is less than 1 hertz, then the structure is treated as a flexible   
i'm sorry there's no quick fix for you here. the nature of what you need simply demands some sophistication.
good luck.
wyf (the polecat)
followup note to my previous posting:
i just noticed the reply to you made by meca consulting.  i also have and use a very comprehensive and well layed out spreadsheet developed by them (called wind95.xls) based on asce 7-95 that will give you the wind pressures i was describing.
wyf (the polecat)
apart from just structural design, you should also study the possibility
of vortex shedding induced resonance in slender stacks. if the problem
is likely you might need to provide spoilers at the top region, which
would increase the wind load significantly, affecting the basic design!
there is an asme standard sts-1 steel stacks which addresses the design of steel stacks which are guyed or unguyed, single or multiple wall, and lined or unlined.  it also covers vibration issues including seismic and wind induced.  it is available from asme for $72.
there is an article that addresses the non-linear nature of the guy wires.  it considers not only the elastic stretch of the cable, but also the sag/span ratio and the initial tension:
a design procedure for guyed stacks applying non-linear cable mechanics, by n. gilbert, y. m. chokshi, foster wheeler energy corporation, houston, tx.
it requires a highly iterative manual solution.  i have gotten bad results using structural design software.  the cable sag and pre-tension is handled poorly by some.  there is a company that has invested in writing a program to perform the design, according to the article, but you would either have to buy the flare from them or possibly pay them to do the design.  
the article was distributed by asme.  there is no date on the copy i have but the newest reference publication is 1968, so it is a vintage article.  it is 8 pages long, if you would like a copy please respond with your fax number.
husker,
could you please send me this fax on guy wires:
name:  chris rosencutter
fax #:  918-355-2913
thanks!
chris rosencutter
question:  why are you designing your own stack?  there are half a dozen companies that specialize in this kind of work and can do a better job faster and cheaper.  the first time designer usually creates a stack much heavier than needed, and many times that can still be inadequate.
the first thing your design must consider is the type of stack required: bare wall, dual wall, insulated, lined?  this determined by your service.
the next thing is the physical location.  is the stack mounted on a rigid foundation?  flexible roof?  is it near another stack or structure that can affect the wind flow?
someone mentioned the use of strakes to break up votices.  this is but one method to mitigate against votex induced vibrations, most designers opt for tuned mass dampers or even damping pads, but these are only required for a minority of the stacks built.  here experience is the rule.
then, the stack design needs to match up with fabrication and erection methods.  is it to be erected as a single unit hoisted into place, or piece meal?  of bolted or welded construction?
there are two available publications to guide the stack designer, the asme publication listed above, and cicind publication (they have a web site), but designing your own stack is a little like designing your own automobile - it's possible, but i won't ride with you!
harvey13,
sorry i didn't see your post earlier.   i have specialized in the design of guyed and self-supporting tower structures for almost 20 years.   this experience has also included structural consulting for the nuclear power generation and petroleum industries.   to my best knowledge, there is only one firm other than my own that has computer software specifically designed for non-linear computation that is capable of the precise and accurate analysis of guyed towers, stacks, and other structures that would be required in your situation.  this company is weisman consultants in downsview, ontario, canada.
recently, ansys released a new fea package that seams to give good results for non-linear analysis, but this software seems a bit cumbersome to run.   also, formation design is offering new software that has tension-only