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# Re: FW: Steel Framing - Aerobic vibration criterion

• To: mStuart(--nospam--at)cmxengineering.com, seaint(--nospam--at)seaint.org
• Subject: Re: FW: Steel Framing - Aerobic vibration criterion
• From: Rhkratzse(--nospam--at)aol.com
• Date: Thu, 23 Jul 2009 17:54:00 EDT

I can't give you any technical guidance, but from a user's perspective if your mezzanine fails the "jump test," regardless of being "economical" no one is going to be very happy.

I was involved in trying to resolve a floor vibration problem, sans aerobics, and believe me, *any* additional original construction cost would have been a bargain!

Ralph

In a message dated 7/23/09 2:48:52 PM, mStuart(--nospam--at)cmxengineering.com writes:
Posted on behave of another engineer at CMX:
Hello All,

I am in the process of designing a new composite slab on steel framing system for basketball and racquetball use as well as cardio activities.    It’s a new 13’000 ft^2 mezzanine.   The approximate column grid is 30’ x 31’.

I am following the requirements for vibration criteria for aerobic type of floors per AISC design guide 11 – Chapter 5.   Per table 5.3, the minimum required floor frequency for an aerobic floor is 9 to 10 Hz.   I am having a difficult time trying to achieve this frequency even after significantly increasing the size of both interior and exterior girders (e.g., W30 x 116 & W24 x 55 respectively) as well as the typical beams (W21 x 44 although for stresses and deflection – even a W14 x22 or W16 x 26 could work).  I’ve even divided the 30’-0” bay into 4 spaces yielding 7’-6” spacing for the filler beams.   These sizes get me a mere 6 Hz?  While it may be possible to achieve the required frequency by increasing the beam and girder sizes even more, the sizes will be so large and uneconomical.

Does anyone have any prior experience designing composite slab on steel framing systems for such vibration criteria?   I am looking for a reality check on member sizes?  Any guidance/suggestions would be greatly appreciated?

Please let me know ASAP.

Thanks.
Ashu Patel, P.E.
Project Manager
Structural Department
CMX
200 State Highway Nine
Manalapan, NJ 07726-0900
Phone (732) 577-9000 ext. 334
Fax (732) 577-9888
website: www.cmxengineering.com

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