For tall guyed structures the analysis can be performed by hand, but it would require about three or four man-months to perform the required calculations that can be performed in a matter of seconds by use of a computer. I plan to write a book on the design of guyed and self-supporting tower structures in the near future (including guyed stacks), but I am unaware of anyone that has written comprehensively and at length on the precise methodology and rationale that goes into the design of these unique structures. A great number of second-order effects will have a significant impact on the design of the structure. This is especially true if your stack is very tall in relation to its diameter. With respect to analyzing this type of structure yourself, I strongly urge you to find a consultant who specializes in the design of guyed structures and has done so for a number of years.
A guy wire software#
Also, Formation Design is offering new software that has tension-only members with second-order analysis, but I have not had a chance to check this software yet. 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. This company is Weisman Consultants in Downsview, Ontario, Canada. 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 experience has also included structural consulting for the nuclear power generation and petroleum industries. I have specialized in the design of guyed and self-supporting tower structures for almost 20 years. 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! RE: guyed stack design Is it to be erected as a single unit hoisted into place, or piece meal? Of bolted or welded construction? Then, the stack design needs to match up with fabrication and erection methods. 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.
Someone mentioned the use of strakes to break up votices. Is the stack mounted on a rigid foundation? Flexible roof? is it near another stack or structure that can affect the wind flow? 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 first time designer usually creates a stack much heavier than needed, and many times that can still be inadequate. 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. RE: guyed stack design Polecat (Structural) 29 Jul 00 09:41 I invite people to visit my website if you wish to discuss these issues further.
The nature of what you need simply demands some sophistication. I'm sorry there's no quick fix for you here.
Here you can get a DOS based finite element analysis program called C-Straad which will solve the nonlinear problem and then interface with a steel design module to size the member. It is used mainly by power companies to design large transmission poles, guyed or not.Īnother source is from Eaglepoint Software in Iowa. The software I use is from Powerline Systems in Wisconsin and will even optimize the diameter and thickness of the steel needed to do the job.
A guy wire trial#
A guyed structure needs to be analyzed as nonlinear and will therefore require a series of trial and error iterations until convergence is reached. Yes there is a software package available that will do what you want, but it is not "inexpensive." No software that can do this will be cheap. If the frequency is less than 1 hertz, then the structure is treated as a flexible member and the gust effect goes up. The gust factor is affected by the shape and natural frequency of the structure. In addition to basic pressure, you will need to account for height, gust, shape and terrain factors.
Just knowing the conversion from mph to psf pressure is only a small part of the problem. First of all, you need to get a copy of ASCE 7-95, Minimum Deaign Loads for Buildings and Other Structures.
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