At 01:34 PM 2006-12-22, [log in to unmask] wrote:
>I may be missing something here, but how does the psf spec depend on what is
>causing the p? Which is heavier, a truck carrying a ton of feathers or a
>carrying a ton of cement?
>I would think that the loading for shelf stacks would be independent of what
>is on them and the library specification would apply.
>However, as all the other comments imply, it depends entirely on the type of
>construction of the building and flooring.
There are several variables at work.
(1) The density (pounds per cubic foot) of vinyl/cardboard 12" LPs
and especially shellac/paper (10" 78s) is higher than most books
(2) Moving-aisle shelving (compactor shelving) is often used in media
storage and not in traditional libraries
Both of these contribute to specific point loads and overall gross
floor loadings that are higher then many other loadings. When I
designed broadcast facilities for a living (1983-2004) this was an
area that I worked with many structural engineers on, but I am no
longer involved, consider some of the work my colleagues and I did on
this NTC company IP and not mine, and don't want to take on the
liability for detailed examination of the specific problem.
It is not always trivial and needs detailed analysis both from the
load perspective as well as the structural perspective. When moving
into our offices almost 10 years ago, NTC had to have a portion of
the high-rise's floor reinforced because we were putting files in
greater density than the building engineer was happy with and those
files were going mid-span. They were only three-drawer high units,
but they were about 30 feet long and two rows back to back (forming a
very nice stand-up meeting table for company wide meetings as well).
Certainly Jim Lindner and I have been around this issue more than
once and I think both of us have provided good advice. We also don't
know how high they want to stack this stuff, but 7' is not uncommon
and I just saw what I think were 8' high moving aisle shelves holding
an audio archive.
My recollection is that film is the heaviest medium, with shellac and
vinyl being up there and then open-reel audio and video tapes being
next. Cassettes are much lighter, but that stands to reason as there
is a lot of air in them.
Richard L. Hess email: [log in to unmask]
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.