Need a book? Engineering books recommendations...

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

Re: Theatre Roof

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Daryl,
I had a similar problem with a pre-eng building.  The
angles coming down from the purlins to the frame
bottom (compression) flange were being struck by fork lifts.  I
recommended stiffeners from top flange to bottom
and new angles from purlins to approx half depth of
girder fastening to new stiffeners.  The pre-eng
people agreed with this solution.
Gary

On 12 Dec 2003 at 9:56, Daryl Richardson wrote:

> Fellow engineers,
> 
>         I'm designing a theatre which will have exposed steel trusses
>         in
> the order of 20' centres radiating from the general area of the stage.
> The span at the centreline ridge is 82'; there are four additional
> trusses of lessor spans, all of which which slope gently downwards
> toward the stage.  To complicate things the roof slope changes,
> becoming less steep at each truss.
> 
>         For aesthetic reasons bottom chord bridging is undesirable.
> 
>         My question(s):
> 
> 1.)  Can I design the truss verticals and the purlins as a rigid frame
> "T" to provide support for the bottom chord via this frame action?
> 
> 2.)  Can I frame a "knee brace" from the mid height of the truss
> vertical to purlins on one or both sides?  I have done this before for
> space frame structures like oil derricks but not for roof structures.
> 
> Neither the AISC or the CISC codes address this problem directly (at
> lease I can't find the reference) so this will be a design from first
> principals.  This does not bother me but there may be other issues I
> am not considering.
> 
>         I have designed triangular trusses with two separate top
>         chords
> and one bottom chord before and I could do it again, however, the
> changes in slope complicate the construction and it may not look too
> good.
> 
>         Any thoughts any of you might have will be appreciated.
> 
> Regards,
> 
> H. Daryl Richardson
> 
> 
> 
> ******* ****** ******* ******** ******* ******* ******* ***
> *   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 
******* ****** ****** ****** ******* ****** ****** ********