Supporting a weight from concrete ceiling

[whiteyfisk]

Somewhat Random question, im a Chemical by trade and so this isnt my area:

Im looking to install a hook in an exposed concrete ceiling that is capable of supporting a person's weight (plus some swinging around so obviously a large safety factor on an average person's dynamic load is needed).

What's the best way to go about this? My first thought was a single, large sleeve anchor. However Ive been advised that using a wood beam, anchored to the concrete via sleeve anchors at several points along its length, with a single hook installed in the wood beam (for supporting the weight), is the best way to go. This ensures that the weight is spread across several anchor points into the concrete, which im told is prone to 'crumbling' (though i dont know if i believe it). The logic is that a single sleeve anchor could be anchored into defective concrete and pull out whereas 4 or 6 sleeve anchors would be much more likely to be OK. The wood is apparently less of an unknown - i know of hooks designed for wood that are suitable to support a person.

Is the use of a beam with several concrete anchoring points correct? If so, instead of a beam, could a steel 'cross' be used (weight supporting hook in the middle, with each tip of the cross being anchored into the concrete)?

The concrete is in a new residential development, i dont have drawings but im lead to believe its 6" thick. I could potentially get drawings from the city, im not sure.

Again civil is not my area so forgive any strange assumptions, etc. Help is appreciated, thanks

 

[bimr]

A 1/2-Inch diameter 6-Inch long concrete wedge anchor has approximately 6,903 lbs of pullout in 2000 psi concrete.

Would think that one 1/2-Inch anchor would suffice.

https://www.confast.com/products/technical-info/thunderstud-anchor.aspx

 

[Ron]

Agree with bimr; however, check and make sure that your concrete ceiling is in fact, cast-in-place concrete. Might be hollow core slabs and if so, wedge anchors won't do so well!

 

[allgoodnamestaken]

Is it a hollowcore slab?

 

[bimr]

Ron is correct. If the floor slab is hollow like the one in the picture, it will be more difficult to install an anchor.

 

[cvg]

two point or three point attachment would reduce swinging and spinning and give you a greater factor of safety

 

[whiteyfisk]

Advice on how to determine if its hollowcore or cast in place? Its a high rise apartment building, im not sure if one method is standard or not...?

Also should i be worried about rebar in the concrete? after talking with some structural at work they inform me 10cm rebar spacing is typical?

 

[JedClampett]

The drawings are the best source. The floors might be part cast in place, part hollowcore. Or they might be prestressed concrete.
You might be able to see the edge of the concrete in a stair well or something. If it has regular round holes, it's Hollow Core. But that doesn't guarentee that it's hollowcore everywhere.
What are you putting in, some kind of sex swing?

 

[whiteyfisk]

Hammock chair (may be used for sex, cant rule that out). there's a big slab of marble near where i want to put it though so potentially pretty bad to have the anchor pull out and crack my head.

alright i'll get drawings from the city and go from there, thanks!

 

[bimr]

The building superintendent may also help.

 

[andriver]

if this is to support a person, OSHA may apply here and thus you would need to support 5,000 lb. minimum. It is possible to do it off a single anchor (there are many products if you just google lifelines). You need to be specific in what is your slab thickness, concrete compressive strength and will this be near an edge (edge distance would apply) just to name a few design considerations.

 

[bimr]

The OSHA rule's 5,000 pound/factor of two requirement is for an anchor that is used as part of a fall protection system, not a fall restraint system. Don't think that is applicable here.

 

[cvg]

if this is a personal hammock in your own residence and not required to be used in your occupation by your employer, than OSHA has no jurisdiction on what you do in your private life. If the anchor breaks and you fall on your head, you can sue yourself

 

[chicopee]

Build you own self supporting framework out of 4X4 lumber which you can dismantle when you are ready to vacate the apartment. Personally, I would not place a hook in the ceiling and if you ask your apartment superintendent for such info, he may take a dim view of your request.

 

[OldBldgGuy]

Oh come on, if you drill & hit air, you'll know it's hollowcore & decide on doggy style. If it's solid, install one anchor as bimr said & rock your socks off.

 

[allgoodnamestaken]

If you drill and hit prestressing strand...

 

[jayrod12]

Your average homeowner isn't buying the drill bits that would stand a chance of drilling through a strand. I wouldn't be concerned in that case.

 

[Ingenuity]

Your average homeowner isn't buying the drill bits that would stand a chance of drilling through a strand. I wouldn't be concerned in that case.

I disagree. They may not drill completely through a strand, but a 1/4" diameter masonry drill bit from Home Depot will sever one (or more wires) of a 1/2" diameter, 7-wire strand, even if drilled overhead, by a 120 lb female.

 

[jayrod12]

Perhaps, but maybe we'll agree to disagree that this happening in one discrete location is enough to cause failure.

 

[allgoodnamestaken]

If you damage a prestressing strand in an apartment you don't own, you're going to be liable for the damage whether it causes an immediate failure or not.

It's an expensive and annoying fix, likely to be done by a contractor the owner hires and paid by you/your insurance (if they choose to cover intentional damage done). Plus charges for arranging said contractor, because you caused the entire problem.

seems like a bad idea to drill into the bottom of a HC slab (or a slab you aren't sure about) all willynilly.