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floor vibration for fitness center with baseketball courts, and etc

floor vibration for fitness center with baseketball courts, and etc

floor vibration for fitness center with baseketball courts, and etc

(OP)
Hi,

I am designing a small building which has complex space programs such as auditorium at the ground floor then fitness center on upper floors. Fitness center has typical weight area, basketball court, instruction studios (aerobics possible), and racquetball courts.

I had a look at AISC design guide and SCI design guide and they recommend some minimum frequency for the floor first. The table (5.3) shows ranges of frenquency from 6.3~10.6 hz.

If the weigtlifting and the aerobics studio are on the same floor should i apply the strictest case: 9.2 / 10.6 hz?

Guide also said something about floating floor or isolating the vibrations. If the floating floor is used can i ignore this 9.2/10.6hz requirements?

Since there is a auditorim below, spans are quite long and it requires very deep and heavy sections to achieve 9 hz and the architect doesn't understand why we need this stiff structure and kept saying he saw tens of fitness centers in the upper floors of the buildings but heard no complaints.

Please help me out on this.

RE: floor vibration for fitness center with baseketball courts, and etc

I hope you have a fellow engineer that knows vibrations that can help on this, as I doubt we are going to be of much assistance. The local expert on this forum is "e"( 271828183), he may be able to provide some good information on the floating floors ect.

What I will say is that the requirement for the higher frequencies is due to the second and third harmonics, generally if you can control acceleration to acceptable levels these higher frequency requirements can be reduced, but you need experience to make this judgement, hence the need for someone that know vibrations.

Arguing with an engineer is like wrestling with a pig in mud. After a while you realize that they like it

RE: floor vibration for fitness center with baseketball courts, and etc

I think you are on the right track, using the AISC design guide.  I designed a second floor dance studio several years ago, with long spans (I think about 50') and I recall using a thick concrete slab, joists spaced closely, etc.  There haven't been any complaints.

DaveAtkins

RE: floor vibration for fitness center with baseketball courts, and etc

Kgr, sounds like you have an interesting problem.  They certainly didn't do you any favors by putting the gym over the auditorium.  You will find it very difficult to make the numbers from the Design Guide work.  The easiest way to stiffen a floor for vibrations is to add columns, but that's not an option.  I'm guessing that the auditorium is slab on grade with sloped stadium seating and that's why it's on the ground floor?  If that's the case, the floor won't really see vibration from the gym, the auditorium should just need noise protection with a high STC rating.  

Whenever you are doing a vibration design, you need to ask "What is causing the vibration?" and "Who/what does it affect?"  If you have a gym and a fitness center on the same floor, the occupants of the fitness center will have a much higher tolerance for vibration than if it were, say, office space.  Unfortunately, vibration also has the possibility to "jump" floors and do weird things to a building that are impossible to predict.  I think if you use some sort of mechanical floor damper, then you do not also need to design the floor for Design Guide #1, it should do the job on its own.  Vibration certainly cannot be ignored though, or you will end up with a very unhappy owner.  The "we've always done it this way" argument should never sway you from what you know is right.

RE: floor vibration for fitness center with baseketball courts, and etc

The frequency is importance to stay away from resonance, but I think the more important consideration is the accelerations.  I understand that the accelerations are influenced by the frequency, but, ultimately, the accelerations will probably drive the design.

Your architect may have seen tens of fitness centers on the upper floors of buildings without problems, but they likely aren't dealing with the spans that you are.

Also, throwing mass at the structure isn't an efficient way to reduce vibrations (and can sometimes even work against you, since you're increasing not just the mass, but also are decreasing the frequency), stiffening the structure is the most efficient way.

I also agree that 27182818 is the man to talk to here.  I'll be waiting for his input.

RE: floor vibration for fitness center with baseketball courts, and etc

One option is to put columns to the roof above to engage any additional damping/ frequency increase resulting from this.

Otherwise as people above have said damping, damping, damping....

Aerobics and dancing are two situations where the people provide the oscillation due to their perfectly timed movements to the beat - definately not to be taken lightly.

RE: floor vibration for fitness center with baseketball courts, and etc

One thing to think about is avoiding repeating bays.  By this I mean that if you've got 4 bays with a 40ft span and purlins 8 ft on center for all of them, then ALL your bays have exactly the same frequencies of vibration. The energy absobtion (i.e. damping) in the system is greatly reduced.  

If I remember correctly, the AISC design guide recomends varying the joint spans and sizes and such to avoid the propgation of those vibrations through the floor system.  

In fact, a prominent vibrations guru once told me that it was essentially impossible to have these types of vibration problems in structures that had skewed and irregular framing.   

RE: floor vibration for fitness center with baseketball courts, and etc

Thomas Murray has a number of research articles you should read before designing this type of floor.  I haven't personally designed a floor for aerobics but I believe you are right that you need to keep the frequency high.  speaking of which the Millenium Mall in Orlando has a floor vibration problem where there is an open atrium.  So watch the end bays where you have spandrel beams ajacent to a balcony open area, etc...  

I Thomas Murray's software and it is excellent.  Don't waist your time trying to iterate your solution by hand or by trying to write your own spreadsheet.  This is a good deal.

http://www.floorvibe.com/

 

John Southard, M.S., P.E.
http://www.pdhlibrary.com

RE: floor vibration for fitness center with baseketball courts, and etc

Someone has already mentioned Thomas Murray. He has had some good articles in AISC's steel journal on this. In the third quarter of 1991 was one such article (and it had criteria for "Gymnasium Environments"; which (according to the article) generally exceeds the 9-10 hz range for natural frequency).

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