Floor plate for safe
Floor plate for safe
(OP)
I am commenting on the appropriate size and thickness of a steel plate that has been used to support a 2000 lb safe with four feet on a wood floor system. The plate and the safe are about 30"x30" and the plate is 1/8" thick.
Between the flexibility of the plate and the floor system and the proximity of the feet to the corners I am having trouble convincing myself that the plate is effective.
Between the flexibility of the plate and the floor system and the proximity of the feet to the corners I am having trouble convincing myself that the plate is effective.






RE: Floor plate for safe
RE: Floor plate for safe
RE: Floor plate for safe
From my initial calculations, the existing joists (16"D I-Joists, 8"oc, 16' span) are just barely adequate at 300psf for the indicated plate size so the configuration should not rely on direct transfer to the joists anyway.
I guess the bottom line is this...if I set a desired LL deflection criteria for the floor system (say L/480 or L/600 for the ATM) then is there a simple way to calculate the thickness of a 30"x30" plate loaded near 4 corners without resorting to some crazy second-order-differential-equation-plate-analysis-deflection-compatibility-study. I'd hate to have to dig out my old university notes ;)
RE: Floor plate for safe
RE: Floor plate for safe
RE: Floor plate for safe
RE: Floor plate for safe
RE: Floor plate for safe
Personally, I'd first check the number of joists that the load needs to be spread along. Then, if space allows, jack the safe up, install a couple of beams between it and the floor to span across the number of joists you calculated, and call it a day.
If space doesn't allow, and the joists directly under the safe footprint are adequate for the load, you may be able to do a similar thing by welding stiffeners to the upper face of the 1/8 in. plate.
From a material standpoint you'll get a much cheaper solution this way than trying to size a plate thick enough to do the same thing.
RE: Floor plate for safe
Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.
RE: Floor plate for safe
What does that mean? It makes no sense. You do not have 300 psf over the 16' span. You have 300 psf over a 30"x30" area.
Treat this as a concentrated load. If your joists are spaced at 8" centers, provide blocking to spread the load over, say six joists. Do not rely on the 1/8" plate to spread the load.
BA
RE: Floor plate for safe
I only applied the 300psf over the given plate size (30"x30") and a standard live load over the rest of the joist. Sorry if that wasn't clear. I only provided the span/depth/spacing as an FYI.
My point was that if the floor just barely works with a uniform distribution over the plate, then there is no point in trying to align the feet of the safe with the joist. The plate and subfloor must be designed to ensure uniform distribution to avoid overloading the joists.
RE: Floor plate for safe
No it doesn't. Whether the total load from the safe is applied as a uniform or as four concentrated loads the load to the joist is almost the same. The subfloor must be design to support the safe load however applied to the joists.
(I do need to learn about how to do the Quote insert.)
Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.
RE: Floor plate for safe
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Floor plate for safe
Depending on the numbers, you may be able to get away with thinner plate than the 1/2", but I'd start there.
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Floor plate for safe
RE: Floor plate for safe
BA
RE: Floor plate for safe