Adding 6,000lbs to a Concrete Floor

Welcome aboard.

Are you friends with this guy?

I'm assuming that you are going to pour the sand in your condo and then fill the room with party goers.

What can you do with 2" of sand that you can't do with 1/2"?

It seems like it would be okay, but I wouldn't recommend it. If it's not okay, it could be catastrophic.

What's going on with you guys in your condos? Just go to the beach.

As you have surmised, there are many different methods of making a concrete structure. I realize that you do not know which method was used, but what you need to do is to check with your local building code authority to identify the load capability for construction built in 2005. They have the authority to say structurally if three tons of sand and all of the people in your party will exceed the rated limit. Speaking from a position of absolutely no authority, three tons is less than the weight of two sports utility vehicles. I'd be very worried if your building cannot support this. Once you have the local building code keeper's blessing, I would certainly contact your landlord and neighbors about your party plans. Remember the easiest way to not disturb your neighbors with a party is to invite them to the party.

Floors are not designed to meet a "standard", they are designed to meet a particular "use". The method of design would be a "standard" and can vary from country to country. Here, up North, we are more conservative with our designs. Our floors would probably look different than your floors, even though they may be subjected to the same conditions.

A floor in an apartment, for example, may have an acceptable amount of deflection that would not be acceptable in a bowling alley. In fact, floor design may vary from room to room, depending on dead load [things that don't move about and self-weight] and live load [people] configurations. The floor would have a built-in safety factor that would accommodate minor variations in loading. While your floor may withstand the extra loading, be aware that once concrete is cracked it is considered "useless", even if it is reinforced.

The top of the floor would be in compression and the bottom would be in tension. Concrete doesn't like tension, that's why there's rebar, and most of it would be in the bottom of the floor. Once the concrete is cracked, the rebar is the only thing supporting the floor and you can be sure that it won't support the floor for too long.

As was suggested, avoid the hassle of dealing with your neighbors and landloard, and take your party to the beach. You can party till the wee hours, or at least until the cops show up. Heck you can even burn a few pallets, paint your faces and dance around buck if you like.

Your residential floor is probably designed for 40psf. Your nutty idea would use up nearly half of that for the sand, and party time is when all the furniture and the maximum number of bodies are there.

That was harsh.

Next thing you know, people will stop posting bad ideas. We don't want that.

Kram, maybe you're right.....

But some people can't see beyond their own nose and think out their actions vs. consequences.

Sorry to have been so blatant and cranky in my response, but I'm dead tired this AM from a very long Planning Board meeting last night that went on and on and on into the wee hours....yeah, I'm one of those #$&(@#!!! guys that sits on a municipal Planning Board who gets to hear whiners and NIMBYs make presentations and protestations and not get paid handsomely for my time and efforts! Hoooo Raahhhhh!

Whaaaa

It's gonna get pretty tough for me to look smart if we run off all the crazy ideas.

We wouldn't have to lose very many people for me to become the dumbest one on here. Take it easy on them.

Passingtongreen - you were dead on with your guess. I heard back from the association and was told the limit was 40lbs per sq. foot.

I appreciate everyone's input, even the blathering rant of CaptM - hope you get some sleep sir!

Have a fun party!

Anyone that's willing to put in that much work is bound to make it a blast!!!

I concur with Kramarat: some of us need these bad ideas to laugh a bit please....

I'm with the Moose on this one. There was also no mention of the method of getting the sand in or more importantly getting the sand OUT. No doubt there would be sand quickly tracked throughout the entire building which I'm sure the other condo owners would not appriciate. As one who knows something about condo's and the laws governing them (as I help manage the Condo from Hell) I see no end to the law suits that could arise from this hair-brained scheme.

Utter Nonsense. Obnoxious language. Sheer ignorance.

Reinforced concrete has an inlay of tor-steel bars and not cardboard.

Steel has a min 350 N/mm^2 tensile strength. Do a simple arithmetic and figure it out.

"Not only the floor, but the beams and columns will collapse". Ho Ho!!

raymenon, I take strong issue with your statements. You appear to not know much about reinforced concrete design, or at least you haven't effectively demonstrated it enough to my satisfaction based on your limited statements in your post. It appears top me that you're originally not from this country.

First you're using metric units. Obviously, the OP lives somewhere in the USA based on his/her statements which he/she has used standard English measurements/units.

Another thing we do not know is the actual floor slab and beam/girder spans nor do we know if they were properly constructed in accordance with the approved Contract Documents (Architect & PE stamped). Also, we don't know the construction history of that particular building and whether there was on-site full time inspection by a Resident Engineer and a testing agency during the placement of the rebar and most importantly the concrete.

In the USA and Canada, reinforcement steel for general construction (there are extreme exceptions to this of course) conforms to ASTM A615 Grade 40 (Yield Stress, fy = 40 Ksi) or ASTM A615 (Yield Stress, fy = 60 Ksi). There's a huge difference between these two rebar grades in terms of strength regimes. We don't know what type of rebar was installed in this building nor do know the actual Compressive Strength (f'c at 28-days age) of the concrete in this fellow's floor slab and it's supporting elements. It could possibly be as low as 1,000 psi or up to 6,000 psi. We don't know it's history whatsoever. It's quite possible that the Contractor placing the concrete "juiced-up" the concrete mix by adding additional water at the project site to aid in it's workability, and hence weakening the concrete strength significantly. Don't say that this is possible because I have actually seen it personally on numerous construction sites over my 34 years as being an engineer. Laboratory testing of concrete cylinders for compressive strength almost always verified that adding water to the mix at the point of concrete placement beared out the significant decrease in concrete compressive strength. So do NDT results of the concrete such as the Windsor Probe Test once the concrete has set.

Also, the tensile strength of the rebar, per your statement, is not the sole factor in determining the overall transformed section strength of a reinforced concrete structural element; the two most important material properties are the steel rebar Yield Strength (fy) and the 28-day age Concrete Compressive Strength (f'c), not the Tensile Strength (ft) of the rebar. If you had actually known this, and had stated as such, you would not had made your grandiose and incorrect statement of fact.

Furthermore, we don't know if the rebar was installed correctly in conformance with the Contract Documents, so it's quite possible that their locations within the suspended floor slab and those within the supporting beams/girders may deviate a significant amount, thus effectively reducing the overall strength of those structural elements a significant amount in terms of Shear Strength and Bending Moment Resistance.

I'd like to add that sand unit weight can vary quite a bit, anywhere from 120 PCF to 135 PCF (depending on actual moisture content) which results in a Live Load of 20 PSF to 22.5 PSF. Factor that in with furniture weight and a crowd of dancing and jumping human beings and it spells a disaster waiting to happen. And lets not forget DYNAMIC LOADING of moving, dancing and jumping drunken party people acting on that floor slab......yes, there's such a thing as IMPACT LOADING FACTOR.

Case in point: When I was attending engineering school for my BSCE way back when I lived in a school-owned apartment complex. One Saturday night there was a huge party happening at another quad within this complex, but quite near by. I and my roomies didn't attend it. I do know some people that did and survived. There were wall-to-wall people within this apartment during this wild drunken party, many of which were jumping up and down and dancing. Some people were actually jumping off of furniture into the crowd or an partially empty portion of the floor.....chairs, sofas and tables. The dynamic loading due to all of the action acting on this apartment floor caused the first floor (wooden floor joists....floor was NYS Building Code rated for 35 PSF) to catastrophically fail and fall into the full basement below. Three people were killed and dozens injured, some critically. I know the circumstances behind this accident because the University and it's insurance company hired one of my Professors (a NYS Licensed/Registered PE/SE) to perform the Forensic Engineering Evaluation and study on the collapse. He later (after court settlements) shared with our Structural Engineering class the reasons for the collapse. BTW, this Professor was a former classmate and friend of my first boss who ran a consulting firm....both of them Structural Engineers for many years and graduates of Rensselaer Polytechnical Institute (RPI) in Troy NY, one of the most premier engineering universities in the USA and world.

I think that's enough about this. I spoke my peace and warned the OP about the foolishness and folly of his/her beach party plans.

There might be something close to a "Beach" already ON the building, most condos I have built have access to the roof, and is all covered with washed pea gravel or beach stones. There are even public/tenant party areas and rooms all ready set up, beautiful views and no one to bug, just the cooling towers and air handling units, but remember, no peeing in the lake or over the side! Enjoy!

I'd use sawdust instead, it's lighter.

Codey

If you still want a beach party, ask the association if you can close off part of the ground level parking lot and put your sand on there. Just make sure to protect any storm sewer inlets in case of rain. Wouldn't want all that sand clogging up the storm sewers and causing a flood.

QUESTION:

Is there a minimum weight rating (i.e. lbs/sq ft?) for the floor that a residential building would have to meet?

ANSWER:

Yes. Suggest you refer to

British Standards (BS) 6339-1:1996: Loading for buildings : Code of practice for dead and imposed loads, BSI 1996.

The normal design imposed load for residential unit is 3 kilo Newtons per square metre or 60 lbs/sq ft. If your floor is not already loaded with heavy staff, the use of 2 inches dry sand for the party should not be a problem.