Concrete Slab Connection 1

[Mark10]

I wanted to ask if it is common practice to specify a polystyrene sleeve over the first 12” of a hairpin-type reinforcement bar that ties the wall footing into a concrete slab. I saw the detail used in an example problem in the book “Masonry Structures”, by Drysdale. It seems like a good idea to allow some settlement of the slab from the footing while still reducing the effective wall height. Since I could not find any other information on this practice, I wondered if anyone could provide any direction or feedback.

 

[JAE]

We have done this for pre-engineered building foundations where the lateral thrust of the column base is transferred to reinforcing "hairpins" or other straight bars into a slab-on-grade. We wrap the first 12" to 18" of bar with a 1" thick foam to allow differential settlement across the distance - allowing the bar to bend slightly while still maintaining a tensile load.

 

[Mark10]

Thank you for helping me out. Do you specify or know of any certain manufacturer of the foam sleeve used for this application? Has this method been effective, both the installation and poerformance?

 

[JAE]

We don't specify the foam itself...just the geometric size/diameter/length. Any compressible material should work fine. We have had good success with this in terms of installation. Long term - no feedback that we are aware of.