huangyhg

floor loading question
i am considering purchasing a raised floor to place couple of digital copiers (xerox docu tech). the floor is a concrete floor made by tech crete. the floor manufacturer says the floor can support up to 450 lb/sq-ft. the uniform load for each machine is approximately 90 lb/sq ft. therefore the floor should be able to support the uniform loading of the machine.
the machine is supported on hard-rubber casters. the concentrated load at the casters is way too high because of the hardness of the rubber and the fact that the wheels are crowned. the concentrated load is approximately 3,000 psi, which is much higher than the maximum concentrated load that the floor can take (1,300 psi based on supplier info). my question is, what would happen to the floor if we put these machines on it? will the floor collapse? will it get some grooves or dimples due to the high concentrated loads?
thanks,
bach4343

ask the floor manufacturer.
you could put the casters on some type of custom wood(2x4)or other type of track to spread the load. the floor manufacturer probably has recs. for this type of application.
is the support system for the raised floor adequate to support the new additional loads?
i've had experience with only one type of elevated floor system. it was a steel frame, with posts at, say, 2 feet c/c each way. the posts were about 18" high. the space below the floor was used to run all kinds of computer wires, telecommunications stuff etc.
the fabricator did a lousy job. the posts and welds looked like they were made by someone who makes steel frames for office furniture. we had some failures. (i did not design it.)
i'd never simply trust the supplier's specifications.
busman's advice is good: use a load-spreading device(s). why not ask the supplier for a full-scale load test?
don't forget to consider the weight of the raised concrete floor. sounds trivial but mistake sometimes made by experienced engineers too.

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