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Re: Steel Framing - Aerobic vibration criterion[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: <seaint(--nospam--at)seaint.org>
- Subject: Re: Steel Framing - Aerobic vibration criterion
- From: "SGE Structural" <sgordin(--nospam--at)sgeconsulting.com>
- Date: Thu, 23 Jul 2009 17:41:05 -0700
Gerard made an excellent point. Any attempts to resolve the problem by the head-on increase of the beam/girder rigidity lead to the cost-prohibitive solutions.
At the same time, the required natural frequency of the floor does not necessarily have to be taken from Table 5.3, it may be reasonably calculated from Formula 5.1.
Let's use Design Guide 11, Example 5.4 as an illustration. Assume wp=4.2 PSF, wt=wc+ws+wp=1.1wc+4.2 PSF; f=2.75HZ, alpha1=1.5. Based on this, to make the floor acceptable (say, fn_rq<=5.4, the concrete slab should weigh about 80 PSF (vs. 65 PSF), or be about 7 inches thick for NWC and 9" thick for LWC.
This is totally doable - build a floor that is too massive to vibrate. Make it 12 inches thick in the exercise hall, you are not in the seismic area, right?
This approach is similar to that used for pedestrian bridges. Such floor will not require any monstrous beams and girders, and may be inert enough not to vibrating. The use of steel will be more effective, too.
Another avenue to explore is the floating floor mentioned in the Design Guide.
Just a thought, and I would still try to contact Dr. Murray.
V. Steve Gordin, SE
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