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Re: beam camber...

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Based on the information you gave and assuming simple spans, the frequency of the floor system would be about 2.4hz which is in the range of footfall frequencies. I'm not sure the occupants of the building would be very comfortable under these circumstances since walking would be easily felt by all occupants and would probably be quite disturbing.
Bill Cain, SE
Berkeley CA
-----Original Message-----
From: dfisher(--nospam--at)
To: seaint(--nospam--at)
Sent: Mon, 30 Apr 2007 3:36 PM
Subject: beam camber...

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List members:
We are currently designing a multi-story office building in Florida.
We have been shown a “prototype” by another engineer with the following
Purlin:              40 ft span
                        100 psf LL
                        5” composite slab (2”+3” NWT)
                        Beam spacing: 10’
                        W18x35 Fy = 50 ksi with 52 shear studs
                        Camber <1 ¾”>
                        DL deflection:    2.14”                 L/224
                        LL deflection:     1.25”                 L/386
                        TL deflection:     3.39”                 L/142
My staff and I think this doesn’t even come close to working, even with the camber.
David L. Fisher SE PE
Senior Director
Cape Cod Grand Cayman Holdings Ltd. - Cayman
Fisher+Partners Structural Engineers Ltd. - Cayman
980 North Michigan Avenue #1640 Chicago 60611
75 Fort Street Georgetown Grand Cayman BWI
319 A Street Boston 02210
312.573.1726 facsimile
312.622.0409 mobile

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