T&S Steel in Plain Concrete?
T&S Steel in Plain Concrete?
(OP)
If I am designing a footing and the it works according to plain concrete design in ACI 22.7, is T&S Steel still required?
My Concern is that the footing/block will crack, but T&S Steel @ 0.0018 still seems heavy.
The design is basically a ballast block sized for overturning.
4ft x 10ft in plan and around 20" thick.
My Concern is that the footing/block will crack, but T&S Steel @ 0.0018 still seems heavy.
The design is basically a ballast block sized for overturning.
4ft x 10ft in plan and around 20" thick.






RE: T&S Steel in Plain Concrete?
Dik
RE: T&S Steel in Plain Concrete?
I also think about the provisions of ACI that have been added regarding cracked concrete and the use of anchors. Not that this applies here....but that the whole basis for that addition, the way I understand it, is that concrete is definately going to crack, and as a result, this should be taken into consideration when designing anchors to concrete. From a big picture standpoint, doesn't that imply we ought to reinforce all concrete?
I guess what I'm getting around to is that its always in good practice to provide reinforcing....in my opinion. I am uncomfortable that there's even a plain concrete section in the code.
Also, the way I read ACI 318, Chapter 22, is that really, plain concrete isn't counted upon as doing much of anything structurally. In other words, the plain concrete must either 1. Be supported itself by soil or structure that will provide adequate support for the plain concrete itself. 2. Must be in compression under all load circumstances or 3. Wall or pedestals (which have additional restrictions in their own portions of chapter 22). Its my opinion, from a big picture review of chapter 22, that, we need to be reinforcing concrete. I can't think of a reason why I'd want to not reinforce something.....as the cost is small to do so.
RE: T&S Steel in Plain Concrete?
RE: T&S Steel in Plain Concrete?
RE: T&S Steel in Plain Concrete?
T&S reinforcement is only required in the perpendicular direction to flexural reinforcement in reinforced concrete. In the flexural direction, other minimums apply. Neither of these would apply to under-reinforced or unreinforced.
Plain concrete should generally not be reinforced less that the ACI minimums, since doing so will likely lead to poor performance and under-reinforced concrete may behave unpredictably. The minimum ratios are selected to provide restraint crack width, but this will not be provided by very low ratios.
While the industry would love to sell you a little rebar or wire, there is no guideline which suggests this is good practice. When I was designing, I always designed with minimum reinforcement where the stresses did not demand more.
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Maybe I should suggest that you go with the minimum for architectural concrete columns...1%. (each way, of course) <wink>
RE: T&S Steel in Plain Concrete?
RE: T&S Steel in Plain Concrete?
RE: T&S Steel in Plain Concrete?
RE: T&S Steel in Plain Concrete?
I would not use plain concrete in a footing where the width is more than twice the thickness. No reference, that is just me.
RE: T&S Steel in Plain Concrete?
Now assume each of the responses above amounted to 10 minutes of time: reading other posts, typing a response, talking about it in the office, etc. That's about 100 minutes. At a billable rate of $125/hr that's about $208.
Macro-economically speaking, it would have been cheaper to put the bars in by this point... then again I'm no economist or contractor, just a sarcastic engineer :)
RE: T&S Steel in Plain Concrete?
I very much appreciate the sarcasm. I honestly do.
But imagine designing and specifying a few thousand of these blocks every year, many of which are for the same customer(s).
Now all of the sudden you've spent a million dollars.
I was trying to optimize the design.
If this was one building or foundation, I wouldn't bother to post the question.
RE: T&S Steel in Plain Concrete?
RE: T&S Steel in Plain Concrete?
EIT
www.HowToEngineer.com
RE: T&S Steel in Plain Concrete?
Again, trying to optimize...not just leave the steel out.
RE: T&S Steel in Plain Concrete?
RE: T&S Steel in Plain Concrete?
RE: T&S Steel in Plain Concrete?
Does this application meet these limitations?
RE: T&S Steel in Plain Concrete?
RE: T&S Steel in Plain Concrete?
RE: T&S Steel in Plain Concrete?
RE: T&S Steel in Plain Concrete?