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Re: [ARSCLIST] Floor Load Capacity
Adding a bit to the comments already made - and giving the disclosure
that I am neither an architect nor an engineer....
The distribution of the weight becomes critical and most of the dead
load issues (this is what is referred to as a dead load as opposed to
a live load) relate not only to the load on a square foot basis but
on the overall load that the structure can handle. For example - even
with 150 pounds per square foot does not assume that EVERY square
foot of the structure will be loaded to capacity. Further there are
other dead loads involved - such as the weight of the structure itself.
Another really important issue is that while the structure may have
been designed for a certain load - that does not necessarily mean
that the "as built" will meet that precise load - unless it was
specifically built and tested to meet that spec. after construction -
there is a long list of shortcuts that can be made during
construction that can severely reduce the designed load - that is why
architects frequently design to a much higher spec. then a building
will normally require for its intended use - because sometimes things
happen - like the concrete not being exactly what was specified or
there being issues with some of the rebar that was sitting in the
rain a bit too long - and so forth.
Also - as a building ages the load handling capacity can change very
dramatically - for example concrete spall is very common in older
buildings and can have a very dramatic impact on the floor load.
Buildings that may have been subjected to previous stress for any
number of reasons may have experienced settling or structural shift
or changes that can cause a big change in load capacity as well. In
the not too distant past a building that I was involved with did a
series of core tests on the roof to determine load capacity and we
were shocked at the results - it seemed that years of water
penetration had caused the concrete to change. The proposed addition
of a patio was out of the question and further work needed to be done
to verify that it would be safe just doing what it was doing as a
regular roof.
When walking around Manhattan these days many of the buildings have
scaffolding up - that is to comply with "local law 10" (http://
query.nytimes.com/gst/fullpage.html?
res=9D04E6D6163DF931A1575AC0A960958260) that relates to masonry
pointing - seems that there are many buildings that need work just
because of exposure over time to the elements and pollution.... there
are many factors that can change the actual load capacity of a
building. Total catastrophic collapse of buildings is very rare these
days due to modern structural design - where the load is distributed
throughout the structure. The idea is not to have just a few points
of failure, but that does not mean that damage does not occur. Beams
can shift and bend, and the damage is not necessarily visible.
There is a very interesting book on this subject - Why Buildings Fall
Down: Why Structures Fail by Levy, Salvadori and Woest
So - I wanted to underscore the comments made and suggest that you
really speak to an engineer and do some tests on the structure and
get an idea of what the real issues are on this specific structure in
the specific condition it is in at this time, and that you seriously
examine this issue.
jim
Jim Lindner
Email: jim@xxxxxxxxxxxxxxxxx
Media Matters LLC.
SAMMA Systems LLC.
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New York, N.Y. 10001
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On Dec 20, 2006, at 2:52 PM, Richard L. Hess wrote:
Hello, Nicole,
this is always a difficult question.
Are you using stationary or moving-aisle shelving?
This should never be done on this scale without consultation with a
structural engineer.
The basic figuring is fairly easy to get close, but the calculation
details should be reviewed with the structural engineer.
First order approximation for fixed-aisle shelving.
Take the linear footage weight of the records (assuming that the
shelves will all be 12" deep and you won't make 10" deep shelves
for the 10" records), multiply the weight per linear foot by the
number of shelves high you plan to stack them.
For moving aisle shelving, you're essentially done as the full load
per square foot is what is required.
You should also have a count of how many records per linear foot.
For fixed-aisle shelving, you'll need to figure out the ratio of
square footage of shelving to aisles and then apply that so you
effectively spread the weight across the whole room, but beware
that the structural engineer will also want to know point loads as
for moving aisle shelving.
150 pounds per square foot is low for moving aisle shelving for
videotape storage, so I suspect it's even less adequate for moving
aisle storage for vinyl/shellac.
Cheers,
Richard
At 01:43 PM 2006-12-20, Nicole Blain wrote:
Hello all,
Does anyone know what the standards are for floor load capacity
for stacks of 12" vinyl and 10" shellac discs.
The standard for library book stacks is ~150 pounds psf. I tried
and failed to find anything on the internet that specifies vinyl
and/or shellac. I imagine it would be higher for the latter. If
there's an official document or study out there too, it would help
convince the architects/engineers that this is an important issue.
I found an article in the Fall 1993 ARSC Journal: Storage of Sound
Recordings by Richard Warren Jr. He has weight per linear foot,
but not floor load capacity.
Our collection houses ~175,000 12" vinyl and ~30,000 10" shellac
discs.
Richard L. Hess email: richard@xxxxxxxxxxxxxxx
Aurora, Ontario, Canada (905) 713 6733 1-877-TAPE-FIX
Detailed contact information: http://www.richardhess.com/tape/
contact.htm
Quality tape transfers -- even from hard-to-play tapes.