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. Mike, 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. Cheers, Richard 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.