New conc floor slab on existing outdoor slab fro metal bldg
New conc floor slab on existing outdoor slab fro metal bldg
(OP)
We are putting up a 40x60 steel Mueller building on an existing outdoor slab 4"+ thick which was poured in the 1950s with no reinforcement. We are looking at doing a 24x24x24" footing at each of the six column feet with a rebar basket in it. The new slab will be 3000psi, 6" thick with #4 bars @16"o.c. each way. The loads I have are:
3x UPS 77"x38" @ 4990# each
12x batteries 74"x15.5" @ 3345# each
CLC Cabinet 77"x38" @ 4277#
transfer switch 36"x48" @ 1100#
These loads should be fine, but I wonder about the forklift wheels, 4"x6" contact patch each. Empty forklift weights 8000lbs and loaded weighs 12,000lbs. Sounds fine to me, but does anyone have any recommendations to back it up?
I am thinking that for the ramp going up is best to cut out the existing old 4" slab and pour in a thicker ramp up onto the new building with thickened edges and maybe more rebar in it, tied into the new 6" slab's steel. Thanks.
3x UPS 77"x38" @ 4990# each
12x batteries 74"x15.5" @ 3345# each
CLC Cabinet 77"x38" @ 4277#
transfer switch 36"x48" @ 1100#
These loads should be fine, but I wonder about the forklift wheels, 4"x6" contact patch each. Empty forklift weights 8000lbs and loaded weighs 12,000lbs. Sounds fine to me, but does anyone have any recommendations to back it up?
I am thinking that for the ramp going up is best to cut out the existing old 4" slab and pour in a thicker ramp up onto the new building with thickened edges and maybe more rebar in it, tied into the new 6" slab's steel. Thanks.





RE: New conc floor slab on existing outdoor slab fro metal bldg
As for the fork lift traffic, an 12000 lb load can be a problem with a 4" slab. I would core the slab in several locations to check the thickness. It is probably less than 4" and will likely vary a lot.
You need to do a little more investigation into the existing conditions before you do the design.
RE: New conc floor slab on existing outdoor slab fro metal bldg
Mike McCann
MMC Engineering
RE: New conc floor slab on existing outdoor slab fro metal bldg
They have cut the existing slab at the six column locations and also trenched across about 40' in two areas, and the minimum thickness is at least 4". So the full floor will be 6" reinforced over 4" plain concrete.
RE: New conc floor slab on existing outdoor slab fro metal bldg
The tied reinforced slab will help with your overturning if the footings are keyed under it.
Be careful with that assumption that the existing footings are OK because a nearby building has the same and it's performing. That type of historical assessment works for soil bearing and settlement, but it doesn't work for uplift and overturning, simply because I doubt that any of the buildings there have been subjected to code mandated wind loads. You are required to design to code...not the owner's wishes.
RE: New conc floor slab on existing outdoor slab fro metal bldg