Concrete Slab Questions Revisited

From what I recall from your original post, there was some discussion of apparent failure in the slab (sagging). A 1920's building that has been used for heaven knows what over the years could very easily have degraded concrete. Original design loads in this circumstance are pretty meaningless. An engineering inspection and actual strength testing is the only way to be sure (other than stacking up a bunch of pallets until the whole thing caves in...)

Live Load is comparible to Dead Weight. Dead weight is not moving, Live load is moving. 90 year old concrete? is it still suporting itself? Don't forget your racking is loading on 4 legs, not divided over the whole rack area.

thanks for reply.

Bldg. and slabs are definitely still supporting themselves. Bldg. has been in continuous use by a number of commercial and retail enterprises over the decades. Most recent occupant was a furniture and appliance store (since the 1940's or 50's). They definitely had many tons of carpets on racks on the second floor. As for cracking, etc. There are surprisingly few,...unlike the slab on grade floors in my garage and equipment sheds! But the bldg. slabs do have a very occasionally hairline cracks that definitely seem more like surface curing cracks rather than structural cracks. But obviously an engineer's eyes need to be found.

Congratulations on finding those prints and labels.

Are your racks loaded at 475 psf throughout? (I don't know if it might be permissible to use an average or some other load factor. Just a thought.)

In the layout of your racks between the existing columns, there might be a way to add some intermediate columns, such as between back-to-back racks. E.g., saw holes in bottom floor, pour footings, build up from there. (Another random idea.)

I don't recall deflection problems from your earlier thread on this; I believe that was a project CaptMoosie was working on.

I would run these ideas by a structural engineer before trying anything, but maybe you have some viable options.

Without getting into the complex details of reinforced slab floor design, I would consider the following.

1. Live working load is any persons or objects the floor has to support. It does not include the floor structure itself, its concrete, steel, etc.

2. Although tempting, I would not use a linear relationship to guess at the load capacity of the 10.5" slab. If the original designers left the capacity out, there must be a good reason.

3. A 3000# forklift carrying 2500# = 5500#/4 tires = 1375#/tire * tire/0.34 sf = 4044#/sf.

4. I have inspected a number of similar old buildings, and they've all had cracks. I would investigate other opportunities for your venture, and leave this 90-year old building for someone else's purpose.

Sorry a 3000# rated forklift (carring 2500#) therefore 3000# rated probably weighs in as 5600 to 9000 lbs! Just for the fork lift. Then the total load onthe floor is somewhere about 10,000 lbs. This load is concentrated in a small area (the forklift footprint) and is a Live Load!

Wow! Thanks for all the info, details, and the time! If you are ever in Montana, you should come by for a look.....and a good Montana micro brew. No hurry. The bldg. has been there and in use since 1920, so I'm guessing it'll still be there in 2020...occupied or not.

I actually did take some photos of bldg inside and out, so could e-mail them.

dave

Blue prints. These look like originals submitted by architects, but my game is organic specialty grains, not construction. Great point about "what you see may not be what is there." Of course nobody from the original building crew would still be around to ask.

Columns. They they are essentially the same spacing in both directions

Rebar. No, the rebar configuration is that of the slabs themselves. Basically concentric rings of re-bar centered over the pillars (radiating out about 5 ft and tied to 8 radial rebars beginning at center) , with 2 x 90-degree grids above these rings going all the way across the bldg. slabs (bldg dims.: 80 ft. x 140 ft) . first grid is North-South/ East-West, second grid is at a diagonal to the first NW-Se/NE-SW. (Wish I had a huge scanner, I'd send you a copy of the slab prints, which would do a better job than my layman's attempt at describing them)

Pillars. Top of pillars do have a square "thickened slab section". Pillars are about 2ft square with thickened slab section probably about 4 ft. where it meets the slab ceiling. I don't have the blueprints handy for exact dims., but this is pretty close. I didn't check column dims on each floor.

Stories. Full Basement + 2 stories above.

Ground water problems. City of Conrad does have ground water issues seasonally due to everyone (over)watering their lawns.

Outside structure. 1 ft. concrete walls--faced w. brick on the 2 sides that face street.

Forklift options. Smaller forklift would certainly be a possibility.....plus that would allow me to put in another row or two of pallet racks. (just joking.... I don't want anyone to have a stroke!)

Freight Elevator. Yes there is one, but no capacity plate. It employs a 1.5" or 2" cable, but I'm guessing you couldn't get more than about a ton of furniture on because it is about8 ft. square.

a sunny day would be good. It was just above zero here this morning.

thanks, so much for your questions and thoughts.

d

Hello David,

You're very welcome! Glad to have helped any way that I could give you, especially given the limited resources we have available to transmit information between us.

Now, all the additional information is making it easier for me to visualize where your concerns and interests weight in with regard to applicability of this building to your needs. A microbrewery (and pub/restaurant) makes perfect sense in an old rustic concrete and brick structure like you have there in Conrad. I've been a quite a few very nice ones in Albany, Troy and Saratoga NY where old warehouses, department stores or factory buildings have been successfully rehabbed/modified into brew pubs. Even in a deep recession like what we've been weathering through these places are still rather busy and successful! With the proper forethought and building a cohesive Architectural and Engineering team you will end up with a very interesting brew pub. Don't forget to cut-in new skylights and multi-story light vaults mixed with live vegetation, hardwoods and brass adornments in the restaurant and bar(s).

A problem that you're going to face is how to support large copper (or stainless steel) vats and the tanks without greatly impacting the floor slabs. One way I'd do it is to suspend the vats and tanks above the existing floors on new structural steel framing and required catwalks/handrails. Of course you'll have to support these new frames with numerous columns (due to the vat and tank weights plus liquid/grain weights) passing down through successive floor slabs (via newly constructed openings....try to miss the rebars!) to newly constructed reinforced concrete foundations located in the basement.

What you have described regarding the radiating and concentric rebar placement call-outs at the column capitals is VERY unique. Not once in my 32 years in this business have I even encountered such an unusual rebar layout in a Two-Way slab!!! That sort of layout makes some sense, and I'd be very curious to know who the design engineer was. Either he was a pure genius or a lunatic! **LOL** Most likely he was an European-trained structural engineer..possibly a German or other northern European that emigrated to the USA. Say, is the City of Conrad a former mining town, as in underground mining??? That may be the true origin of your structural engineer or from another mining town in Montana or other neighboring state.

David, many thanks for the offer to look over the building and visit Conrad! I really wish I could do that......just pack-up and jet out there in a whim! LOL I've never been to Montana, but always wanted to before I kick the bucket. Beautiful Sky Country indeed!

You can seen scanned pics to my private email address, but first you must contact me via my CR4 Forum mailbox. I would love to see the pics!!!!

Have a great day!

Captain Moosie is definitely racking up the GA votes on this one.

I have to say David as well, I for one appreciate the tone of your inquiries.

Where and how did you find the plans?

All that rebar, thickness of the slab, and 100 pound per square foot live load strikes me as oddly low, too.

I worked in a Motion Picture Studio mainly built of wood where we were warned that the floors were only good for 200 pounds per square foot, so find the floor rating according to plans strange in comparison, regardless of whatever the rebar shaping and cross laydown.

Frankly it sounds like a sturdy building to me.

Thanks for getting back to us with some more of the story.

Hope you will post some pictures for all of us to see.

P.S. Since you got ahold of the plans, and there must be some names on them, and the architects, and engineers likely worked in your area on more than one building, is there any other building with a history to compare?