Reinforcement of Lift Points - Precast Concrete Slab

[Trillers]

Does anyone know of a good reference or procedure to determine stress around lift points on a PC slab?

Want to know how to detail reinforcement at those lift points - any references?

Thanks.

 

[ztengguy]

Check with the manufacture of the lift insert that will be used. Sometimes they dont require additional reinforcing, and just count on concrete strength.

 

[CANPRO]

Second the suggestion to look at the manufacturer's data. See link below to Dayton Superior...there are some allowable loads for various products and they go through the strength calculation for the concrete. Be careful when using the allowable loads because a lot times they're based on a much higher strength than what will be available when the panel is stripped and first lifted.

http://www.daytonsuperior.com/Artifacts/DS_Precast_HB.pdf

 

[KootK]

At the lift points, classical stress isn't likely to have much meaning. You'll likely be dealing with cracked concrete and anchorage principles. Manufacturer's recommendations backed up by testing are definitely the way to go.

The closest thing to a stress check that I can think of would be a punching shear check. Counter intuitively, however, that won't lead you to a flexural reinforcing requirement.

The greatest trick that bond stress ever pulled was convincing the world it didn't exist.