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Re: elevator hoist beam

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I thought this thread brings up an interesting dilemma.  At least to me.  On
some projects, it is expressed or implied that the engineer produce a set of
drawings that are ready for bids before some of the finer points of the
building have been established, mainly HVAC and in this case, elevator
loads.  We already have a CYA note for mechanical units.  Other than relying
on past experience with similar types of buildings, isn't using the 5 kip
load for a hoist beam reasonable for most low-rise buildings?  I assume most
would design for double that load to account for impact, according to the
AISC code.  I have used this general rule (although I seem to recall it being
mentioned in BOCA or the steel code?) on a number of 3 story or less
buildings in a low-seismic zone with no problems.  The draftsmen I work with
have also, I guess by repetition, shown a W8x24 as the hoist beam for the
last 30+ years, which predates my engineering experience by quite a bit and
comes from either my boss or a standard detail.  Granted, the original poster
didn't say how many stories are in his building, but, my question is, not
being aquainted with the subtle intricacies of elevator supports, is this
assumption no longer valid for low-rise buildings or should I make a point of
requiring a set of cut sheets from the elevator supplier?  Again, bear in
mind that some clients don't have this information until it's too late, i.e.,
they're doing tests on 28 day concrete cylinders for the foundations.

Mark Nowmos


Jeng-Wei Li wrote:

>
> I have the same question before, here are the response that I got from the
> elevator contractor:
> You need two reaction force at the elevator pit: the R5(cage site
> reaction),R6(CWT side reaction)
>
> Cage Weight,Wc & Load Weight,Wl
> Peopleã??                        6     8      9  10   11   12   13     15
> 17
>       Cage Weight (kg) 750 780 800 840 870 900 930 1040 1300
>       Load Weight (kg) 450 550 600 700 750 800 900 1000 1150
>
> Buffer Ramp,S
>       Speed (m/min)  60   90-105   120      150     180      210     240
>       Ramp(m) ã?? 0.102     0.212  0.27   0.425  0.608   0.828  1.081
>
> This is my calculation example:
> Reaction force
> 2.1 Reaction design data
>      Buffer Type:Actuator
>      Cage Weifht, Wc=   1300 kg
>      Load Weight, Wl=   1150 kg
>      Buffer Ramp,S=   0.212 m
>      V=1.4Vd=    2.45  m/sec   ,Vd=design speed
> 2.2 Cage Side Reaction, R5
>      W=Wc+Wl=    2450  kg
>      R5=2W(1+V^2/(2gS))=   11978  kg, g=9.8m/sec2
> 2.3 CWT Side Reaction, R6
>      W=Wc+Wl/2=    1875  kg
>      R6=2W(1+V^2/(2gS))=   9167  kg, g=9.8m/sec2
>
> Hope this will help.
>
> Jeng-Wei Li,SE
>
> ----- Original Message -----
> From: "Daryl Richardson" <h.d.richardson(--nospam--at)shaw.ca>
> To: <seaint(--nospam--at)seaint.org>
> Sent: Friday, February 01, 2002 12:50 AM
> Subject: Re: elevator hoist beam
>
> > David,
> >
> > You had better talk to the elevator supplier.  5 kips might be a bit
> > light for some elevators.
> >
> > Regards,
> >
> > H. Daryl Richardson
> >
> > David Adie wrote:
> > >
> > > does anyone know of a good design reference for elevator hoist beams?
> > >
> > > my superior told me to load a simple span beam with a 5 kip point load
> > > applied at the middle.  is that about it or is there more involved?
> > >
> > > tia
> > >
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