Threaded Shear Connection 1

[05dtaylor]

Background:
6'x 12' ID Concrete Tank with 5" Walls. I'm working with the bottom half of this tank. The height of this piece is 4'-3" Tall. It has 5" thick walls and a 7" thick base slab. It's monolithic.

This piece will be filled with a large amount of concrete to form some channels for a sanitary system. Estimated weight of the tank section is ~16,000 lbs and estimated weight of the concrete to be poured inside this section is 28,000 lbs. Due to the channel design, the lifting points will be located in the top face of the poured insert. Long "dog bones" will be used as lifting inserts. One placed at each corner located 12" away from both walls.

What i'm trying to figure out is how to attach the inner concrete to the tank so as to properly be able to lift this entire piece at once.

My boss wants to use Dayton threaded rebar splices as connections between the interfaces. According to dayton, a #4 female end splice has a minimum depth of 4" which means it would be able to be placed in the walls. a #6 female end splice has a minimum depth of 6" which means #6, #5, or #4 can be placed in the base slab.

I'm trying to figure out the shear capacity of the #4 connection.

Any help? or ideas?

Thank you

 

[JedClampett]

I'm trying to get my head around what you're describing here. Do you have a sketch? Do you need to lift by the interior walls so they need to be attached to carry the weight? Or are they just along for the ride?
I guess I'm confused by the fact that you're precasting something this heavy and flying it into place.

 

[05dtaylor]

Here's a pdf that shows what it is.

 

[JedClampett]

Now I'm not sure why you need the shear capacity of the #4. Is it because of the rigging angles? These look like tension loads only.
But long story short,you need to get a copy of ACI 318 and go to Appendix D. It's a miserable document, but it's the code. I wouldn't place a whole lot of stock into Dayton Richmond's allowable loads. They're going to be hard to find if that thing falls.

 

[dhengr]

05dtaylor:
I assume the outer tank is reinforced and intended to contain the process. The inner conc., an incredible quantity and weight for the purpose, is intended to form the channels and center island and gate structure. I’d make 60% of that inner conc. volume out of foam glued to the walls and bottom of the outer tank. With little effort and some changes to the inner form for the tank, you could cast lugs and/or keys (shear lugs with an allowable conc. shear stress) which would then key into the inner cast conc. and carry the 16kips. Any steel crossing the cold joint stands a pretty good chance of getting wet and staying wet and may deteriorate. Alternatively, you could run your lifting bars from a 12x12", or some such, steel plate on the outside, bottom corners of the tank, and extending up through the second, inner, pour to a lifting eye, and avoid the entire ACI 318, Appx. D.

 

[05dtaylor]

Why didn't I think of the foam? Thanks for the help.