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RE: controlling vibration on existing steel joist floor

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Take a look at this article from Modern Steel Construction

http://www.aisc.org/MSCTemplate.cfm?Section=Modern_Steel_Construction2&t
emplate=/ContentManagement/ContentDisplay.cfm&ContentID=27046

If the link doesn't work, it's the article in the December 2004 issue of
the Modenr Steel Construction.  It talks about an active control system
for reducing floor vibration.


Y i   Y a n g,   P. E.             
STRUCTURAL DIVISION
SUMMIT ENGINEERING INC.
707.527.0775.x15
Santa Rosa, California
 


-----Original Message-----
From: Harold Sprague [mailto:spraguehope(--nospam--at)hotmail.com] 
Sent: Wednesday, January 05, 2005 3:09 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: controlling vibration on existing steel joist floor


Pedro,
The first time I saw this as a problem was for a shopping mall designed
in 
the 1960's.  The most effective solution then is the same as it is now.
Use 
a tuned mass damper.  Back then it was some formed concrete weights 
suspended by springs.  Adding stiffness costs more than it helps.

Today, you can use tuned viscous mass dampers.

There is a program sold by the Steel Joist Institute that you might find

handy.  The SJI also produces a publication, TECHNICAL DIGEST #5 - 
VIBRATION, you might find useful.
http://www.steeljoist.org/publications/

In my foolish days of youth, I slept on a vibration sensitive pool hall 
floor, but that is another topic.

Regards,
Harold Sprague




>From: "Pedro Khouri" <khouri_p(--nospam--at)hotmail.com>
>Reply-To: <seaint(--nospam--at)seaint.org>
>To: seaint(--nospam--at)seaint.org
>Subject: controlling vibration on existing steel joist floor
>Date: Wed, 05 Jan 2005 17:21:32 -0500
>
>(Sory if a repost)
>
>Does any one have recommendation on controlling vibration on existing 
>steel
>joist floor.
>
>The floor is supporting pool tables in a open room with no partitions.
>
>The floor system is concrete (do not know the thickness) over metal 
>deck
>supported by 24" deep joist (Vulcraft 11 J 2 per attached tag) spaced
at 
>24" O.C. with a clear span of approximately 48 ft.
>
>The contractor is subjecting the addition of a mid span support with 
>some
>posts to the room bellow to reduce the joist's span. I am concern that
the 
>added support will negatively affect the joist by inducing negative
moments 
>at mid span although the joist members (top / bottom chord & web
members) 
>appear to be constant thru the length of the joist.
>
>Any comments will be appreciate.
>
>Thank you,
>
>Pedro Khouri, P.E.
>
>Coral Springs, FL
>

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