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comm#870--Distributed Floor Loads

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Mitch,
I recently did a couple of buildings with UPS systems such as you describe.

> Okay, now here is the twist, the Battery Cabinet is supported by 8
> wheels @ 471#. How would you handle the concentrated stress?

Un-concentrate them.  At a minimum, call for a couple of channels or
something similar for the wheels to ride in, with field welded stops if
needed.  Better yet, make a grillage (perhaps W4x13 or similar) with 1/4
inch floor plate on top, making sure a beam ends up under each wheel.  Your
electrical guy will love you, because now he has a chase to run cabling
under the cabinet.  (He will love you in direct proportion to the depth of
the grillage, so maybe bump up the beams.  UPS cabling tends to be bulky,
with large bend radii.
Ask him what he needs.)  Then, obviously, make sure the grillage crosses
your floor beams (rather than lying between them), or put stout diaphragms
between the floor beams to pick up the grillage beams.  (In other words, I
wouldn't use the floor slab in shear under concentrated loads like this.
There's no real reason to for such a small area.)

It's probably a good idea to note the design load on the plans, as well as a
stern note warning against relocating it.  And, as noted in a previous post,
you'll want to satisfy yourself that the unit can be brought in and placed
without breaking something.  Sometimes they're dividable, sometimes not.

If looks matter, give your architect a chance to put a nice vinyl skirt
around the thing.  He'll love you too.

Mike Hemstad
TKDA
St. Paul, Minnesota


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