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Re: Suspended Speaker

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Alfonso,

Off the top of my head, I am not aware of what code provisions may apply
to this situation.  I for one, would be uncomfortable suspending this as
freely as I get the impression by your description.  With all of the
horizontal, vertical and rotational movement, are you comfortable the
connections at the top and bottom of the suspending element will not be
compromised?  It also seems like this will generate an impact load on
the bottom chord of the truss in all 3 directions.

My first impression is that I would be more comfortable rigidly
attaching this to the diaphragm.

Jeff Coronado, S.E.
West Covina, CA 


Alfonso S Quilala wrote:
> 
> I think the question I supposed to ask is, "Is it allowed not to
> seismically brace the speaker due to the reason I previously mentioned
> (seismic is not required for elements that are suspended and free to
> translate during a seismic event for more than the expected earth
> displacements)."
> 
> The speaker by the way will be installed in a high school gymnasium
> and auditorium.
> 
> Thanks again!
> 
> Alfonso S. Quilala Jr., P.E.
> 
>      -----Original Message-----
>      From: Mark D. Anderson PE [mailto:mark(--nospam--at)alaskaengineer.com]
>      Sent: Wednesday, February 07, 2001 2:56 PM
>      To: seaint(--nospam--at)seaint.org
>      Subject: Re: Suspended Speaker
> 
>      Are you looking for something beyond footnotes 11 and 12 to
>      Table 16-O in the 1997 UBC?
> 
>      Mark D. Anderson PE
> 
>           ----- Original Message -----
>           From: Alfonso S Quilala
>           To: 'seaint(--nospam--at)seaint.org'
>           Sent: Wednesday, February 07, 2001 9:10 AM
>           Subject: Suspended Speaker
> 
>           I am reviewing a submittal consist of 300 lbs.
>           speaker cluster that is to be suspended using an
>           aircraft cable.  It will be attached to the
>           midpoint of a bottom chord of a truss.  The
>           Structural Engineer noted in his calcs. that
>           seismic is not required for elements that are
>           suspended and free to translate during a seismic
>           event for more than the expected earth
>           displacements.  I think that I have read this note
>           somewhere before but I can not recall where.  I
>           tried to asked my co-worker and tried to look at
>           the Code but I can not find it.  Will somebody
>           point me where I can find it?
> 
>           Thanks a lot in advance!
> 
>           Alfonso S. Quilala Jr., P.E.