Looking for suggestions on lifting device

[jmen68]

I am demoing an old reinforced concrete 10 inches thick, we will be saw cutting the deck into pieces ranging from 15' to 20' long x 4' wide (about 8,500 to 11,000 lbs). I am looking for unique suggestions on how to attach my rigging to the cut pieces. I will have no access to the bottom side so my initial thought of coring a hole then attaching a plate washer + nut to an eye bolt is not feasible. I have also explored making a lifting eye plate, then anchoring it to the surface of the concrete, but that will just be to tedious and to many anchors to purchase.

Anyone have any suggestions or an off the shelf type product that could help? I have attached a picture of the original plan, but keep in mind that wont work as I have no access to the bottom. thanks!

 

[JGard1985]

Why not a flush mount undercut anchor like a drillco maxi-bolt. You could then thread your lifting eyes into the threaded collar. Under cuts have much better capacity than typical expansion anchors. Anchors could be , but not as much as coring through. 1/2" anchors with standard embedment are rated for 7,105 lbs in tension with a 6" embedment

See attached link

http://www.drillcogroup.com/maxi_bolts/general/flush.html

Jeff
Pipe Stress Analysis Engineer

http://www.xceed-eng.com

 

[oldestguy]

I'd core 3" diameter holes through, maybe two per slab piece. Drop down a "grabber". To release it, pull on the wire.

 

[chicopee]

We used Pelican hooks to lift heavy structural steel plates. I would explore cutting slots to depth below top grillage of rebar and then insert these hooks under the grillage. The caution is that if the pelican hooks are not fully inserted their rated strength is diminished by the manufacturer specs.

 

[oldestguy]

This pipe may be easier to use and more durable. Make the overall width at lug just short of 3" to fit in the 3" core hole. Drop the "L" piece down opposite the lug. the lifting bail needs to be sufficiently far up so as to not interfere with jamming the "L" piece in. The"L" piece might be more usable if it is 1/2" by 1" strap and still work . Maybe also flatten the lower end of the pipe some, to make clearnce on the opposite side of the lug. Then weld in a plug to keep it from collapsing further under major loads.

 

[LittleInch]

This might be a bit off the wall, but what about a few climbing link cam fixings. Just drill a few holes then insert the cam device. They seem to be rated about 14 kN, say 3000 lbs, but once used detach easily so you can use it again. You wouldn't have to drill the entire depth.
Search rock climbing link cam.


Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Compositepro]

You could make a suction cup from steel plate and plastic film or rubber sheet. Suction can lift over 1500 lbs. per square foot. Vacuum can be generated with an eductor (venturi) using compressed air.

 

[btrueblood]

It sure seems from here that the quick and easy way is to fab up a couple of lifting plates with a welded lift eye sized for the anticipated load, and a set of 1/2" bolt holes in whatever pattern you prefer. Send a lackey onto the slab with a rock drill, a box of cheap 1/2" anchor bolts, and both plates. Set plate, drill holes and set anchors, attach plates and hoist away.

Why cut the chunks so darn big, though? Are you planning re-use in a retaining wall or something?

 

[Ingenuity]

then anchoring it to the surface of the concrete, but that will just be to tedious and to many anchors to purchase.

Concrete screw anchors are reusable and only require a match-diameter drill hole and an impact wrench to set and release.

On this 3000lb concrete roof slab we cut and lowered last month, we used 5/8"Ø HILTI EZ anchors and 3/8" thick angle plates.

For your application, with heavier loads, a 2-bolt T-plate/eye-pad at each end, screw anchored and embedded 8" into the panel should work depending on the anchor diameter, and very quick to set and re-use.

2-point lowering of panel:

Steel angle lifting eye and shackle to top of panel:

HILTI EZ concrete screw anchors:

 

[oldestguy]

Screw anchors seem to be common in use. I would have a hefty safety factor applied to any tables, such as the in the link here.

https://www.confast.com/products/technical-info/tapcon-concretescrew.aspx

 

[Ussuri]

Can you put in a small fixing at one end, sized just to lift the end of the ground, and then run lifting slings under it, in a basket hitch. Repeat for the other end?

Means you don't need as big FOS on your anchors?

 

[bridgebuster]

Compositepro's suction cups aren't that far-fetched. Take a look at this:

Link

I was on a project, way back, where the contractor took out the bridge deck in 8'x30' panels. He core drilled the slab and used a two-piece pin to pick it. The product in this link is a little more sophisticated than the pin I remember

Link

I also like Ingenuity's idea. What are you demo-ing, roof slab, bridge deck?

 

[ameyerrenke]

I would go with post installed anchors using Hilti HY200 epoxy personally. May not be the cheapest, but I trust it, and have some on the shelf down the hall from me!

 

[fel3]

Gerd Bonk

https://en.wikipedia.org/wiki/Gerd_Bonk

==========
"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill

 

[JGard1985]

jmen68,

Can you update us? What did you eventually decide to do? Can you share a picture?



Jeff
Pipe Stress Analysis Engineer

http://www.xceed-eng.com

 

[jmen68]

Sure thing JGard1985. Well all of these suggestions were great in their own way, the one I liked the best was from user bridgebuster. The monkey fist product looked to fit the bill, and a quote from Maxwell Supply, the sellers of the monkey fist product, came in about $350 US a piece which was do-able... here comes the however. I did say that we had no access to the bottom of the slabs, which was why I needed the unique solution. That wasn't particularly true, there was access, but it was through about 3 ft of muck. We had already determined it wouldn't be cost effective to remove or stabilize just for access. Also this particular job was a small city job that we needed a DBE contractor to preform this work. So as DBE contractors do, they went ahead and sent the low guy on the totem-pole to dredge through the muck use a step ladder and secure a plate washer and nut to an eye bolt threaded through a hole cored through the slab. Very inelegant, but effective and cheap. No pictures sorry.

Thanks again for everyone's suggestions, this is a great community, and hopefully I can help others with some ideas down the road too!