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StructuralEng
StructuralEng, Consultant
Category: Structural Engineering
Satisfied Customers: 6865
Experience:  Structural Engineer
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I hung an aerial hammock into a concrete ceiling. Am I saf

Customer Question

I hung an aerial hammock into a concrete ceiling. Am I safe?
Submitted: 10 months ago.
Category: Structural Engineering
Expert:  StructuralEng replied 10 months ago.
What kind of concrete is it? On metal deck? Thickness?
Customer: replied 10 months ago.
It is an apartment building that is approximately 4 years old. I'm on first floor. There are 6 floors. I don't know about thickness. I weigh 137lbs and want to do acrobatic/tricks type stuff from the hammock.
Expert:  StructuralEng replied 10 months ago.
Do you know anything about the slab?
Customer: replied 10 months ago.
No. And I'm pretty sure it's against my lease to have hung it, so I can't really ask! Yikes! Is there another way I could get that information to give to you?
Expert:  StructuralEng replied 10 months ago.
Do you believe it to be structure? Not just a finish?
Expert:  StructuralEng replied 10 months ago.
It appears to be hollow core plank. You have to be very careful drilling into it to not damage rebar or prestressing cables. The additional load on the plank is not a concern, but the connection capacity could be and possibly damaging reinforcing.
Customer: replied 10 months ago.
Do you mean do I think it's concrete the whole way through? Yes. We had to rent a stronger drill and use drill bits for concrete to get through. It was difficult to get the anchors in and it felt very solid. I don't know what you mean by damaging reinforcing?
Customer: replied 10 months ago.
Actually, there was a space between the floors. As in, we drilled in a ways, and then there was space. Then the floor above.
Expert:  StructuralEng replied 10 months ago.
These elements are precast in a concrete plant. They have steel reinforcing and prestressing cables. If you cut those when drilling, it's a big problem.
Expert:  StructuralEng replied 10 months ago.
Yes, that is what you would get with hollow core plank. It's a concrete slab with circular sections taken out of the middle
Customer: replied 10 months ago.
So when you say big problem, what do you mean?
Expert:  StructuralEng replied 10 months ago.
I mean if you damaged reinforcing steel or prestressing cable and the building owner finds out about it you will likely be paying to repair it. It will be a quite expensive repair.
Customer: replied 10 months ago.
Okay. Yep. I realize there is a risk. How about my safety using it?
Expert:  StructuralEng replied 10 months ago.
What kind of concrete screws did you use? How much embedment did you get before hitting the void?
Customer: replied 10 months ago.
I have this picture. I'd have to ask my boyfriend for more info and he isn't available at the moment. Does the picture help? Or do you need more specifics?
Customer: replied 10 months ago.
Also, now you have me a little freaked out. The ceiling is not going to fall down, correct??
Expert:  StructuralEng replied 10 months ago.
I can tell it's an expansion anchor. That's it. The diameter, embedment, etc. I can't tell.
Expert:  StructuralEng replied 10 months ago.
I don't expect anything catastrophic, but if anything was damaged and they find out, you'll likely be on the hook for it.
Customer: replied 10 months ago.
Okay. Thanks. If I get more information about the can I reply to this thread at a later date and get a response from you?
Expert:  StructuralEng replied 10 months ago.
You can come back to this chat string

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