Reinforcing Bar Development Length
Reinforcing Bar Development Length
(OP)
I am designing a spread footing for a lightly loaded metal building. I am using a 24" x 24" x 18" deep footing. The punching shear and beam shear check okay and there is enough reinforcing to help with the bending moment. The baseplate is 12" x 8". I am using 3000psi concrete, 60,000 psi yield strength #4 bars. With this combination I end up needing approximately 13.5" of development. As you can see with the 24" x 24" footing and the baseplate above I don't have it. Is there anything I can do to achieve my development length without going to a larger footing.





RE: Reinforcing Bar Development Length
If builiding codes, type loading, etc. allow, perhaps you could consider using an unreinforced footing.
RE: Reinforcing Bar Development Length
Sorry to get in before the question is resolved, but I wonder where you're getting these different values for Db? I've tried to chase down development length in the 97 UBC (I assume still the same in the IBC), but wasn't able to nail it down to a specific formula. This should make for a simple answer. Thanks.
RE: Reinforcing Bar Development Length
lumbee - Other ways to look at your situation:
1. If you could increase the compression strength of the concrete, this would shorten the development length required (a minimum value may apply however).
2. If your design could be based on Grade 40 reinforcing steel stress the development length would also tend to shorten. You would have a few more bars, but it might solve your problem. You could still use Grade 60 (it is probably more readily available than Grade 40) as long as the placement was in accordance with your Grade 40 calculations.
RE: Reinforcing Bar Development Length
DaveAtkins
RE: Reinforcing Bar Development Length
RE: Reinforcing Bar Development Length
RE: Reinforcing Bar Development Length
If you really want to develop the bar why don't you specify a "U" shaped bar with a standard hook on each end and turn the hook up into the depth of the footing?
RE: Reinforcing Bar Development Length
RE: Reinforcing Bar Development Length