Return to index: [Subject] [Thread] [Date] [Author]

Re: Information on design of steel chimneys

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Fellow engineers,

	Guyed steel stacks are a specialty of mine.  I would strongly recommend
that anyone seeking information on the internet to carry out a stack
design when they are not experienced in stack design proceed with
extreme caution.

	There are several important features of guyed steel stacks which set
them apart from most other structures.  Some of these are:

1.)  Wind loading is critical.  Wind loading should be determined as
part of dynamic analyses.  Canadian wind loading procedures do a very
nice job of this.  I haven't tried to design a stack with U.S. wind
loading procedures but I would suggest a dynamic impact factor of about
1.5 if you are attempting to use static wind loading procedures such as
I have used for other U.S. projects.

2.)  Vortex shedding may or may not be critical but it is imperative
that this be checked, preferably dynamically.

3.)  P-Delta analysis is mandatory!  The resulting moments might be as
much as 50% of the wind load moments.

4.)  Guys do not have the same tension, therefore, the eccentricity of
the guy connections must be considered.  This may seem obvious but it's
often overlooked.

5.)  Local buckling considerations for thin shells may govern the
allowable stresses.

6.)  Temperature considerations may (probably will) be part of the
governing loading condition.  For taller stacks, sun shielding of some
guys may become important.

7.)  Guys are non linear; they should be analyzed as catenarys.  Beware
of programs which use parabolic formulae as they may determine
compressive load in the guys.

	Free standing stacks are much more simple to design but some of the
considerations listed above still apply

	I hope this is helpful.

				Regards,

				H. Daryl Richardson

JamesFulton(--nospam--at)Rohmhaas.com wrote:
>
> Speaking of steel stacks, anyone know of any good programs for analysis of
> the pretensioned guy cables in guyed stacks ? For unsymmetrical guy cable
> layout (plan and elevation) the analysis is very complicated. For
> symmetrical
> cables, it's much simpler and only some simple formulas are needed.
>
> ______________________________ Reply Separator
> _________________________________
> Subject: Re: Information on design of steel chimneys
> Author:  <seaint(--nospam--at)seaint.org> ("Kipke, Richard" <RKipke(--nospam--at)Haden.com>) at ROH
> Date:    2/22/2002 8:51 AM
>
> Try mecaconsulting.com
> They offer a couple of programs and spreadsheets for designing steel
> stacks.
> I haven't used them, but they look useful.  Even if you are not interested
> in the program, they have a page of errata and changes for  the ASME
> STS-1-2000 (latest ASME Code).  Anyone who has the 2000 code should at
> least
> review that page.
>
> SMACNA also has a stack guide - which I've never cared for and might not be
> very current.
>
> Lincoln Eelectric's Tubular Steel Structures is still available on their
> website.  It has a couple of chapters on chimneys - again not the most
> useful reference.
>
> Rich
>
> ******* ****** ******* ******** ******* ******* ******* ***
> *   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
> *
> *   This email was sent to you via Structural Engineers
> *   Association of Southern California (SEAOSC) server. To
> *   subscribe (no fee) or UnSubscribe, please go to:
> *
> *   http://www.seaint.org/sealist1.asp
> *
> *   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you
> *   send to the list is public domain and may be re-posted
> *   without your permission. Make sure you visit our web
> *   site at: http://www.seaint.org
> ******* ****** ****** ****** ******* ****** ****** ********
>
> ******* ****** ******* ******** ******* ******* ******* ***
> *   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
> *
> *   This email was sent to you via Structural Engineers
> *   Association of Southern California (SEAOSC) server. To
> *   subscribe (no fee) or UnSubscribe, please go to:
> *
> *   http://www.seaint.org/sealist1.asp
> *
> *   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you
> *   send to the list is public domain and may be re-posted
> *   without your permission. Make sure you visit our web
> *   site at: http://www.seaint.org
> ******* ****** ****** ****** ******* ****** ****** ********

******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
*
*   This email was sent to you via Structural Engineers
*   Association of Southern California (SEAOSC) server. To
*   subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you
*   send to the list is public domain and may be re-posted
*   without your permission. Make sure you visit our web
*   site at: http://www.seaint.org
******* ****** ****** ****** ******* ****** ****** ********