Rebar Spacing

[marinaman]

I was just thinking about something I saw today and was wondering in my mind......

If a cast-in-place concrete retaining wall is designed to have #7 bars at 4" o.c. on the tension face as vertical reinforcing, does that meet the ACI criteria for bar spacing minimum?

The reason I ask is, if the wall is reinforced with vertical #7 hooked dowels, and is lapped with #7 vertical bars at 4", then the distance between sets of bars would be 4" minus (2)(7/8") which would be 2 1/4" clear.

As I recall, the spacing minimum is one bar diameter clear, or at least 1".

Is there any ACI provision requiring more spacing than this? I don't know of any, I was just thinking about it and wondering if there was.

I was just thinking about development length, splice lengths, and overlapping engagement of the concrete about each splice.

 

[jayrod12]

I don't know about ACI but I think CSA is 1.4db minimum. And our codes mimic each other very well.

 

[KootK]

Yeah, there's also a spacing limit relative to aggregate size but it would be okay there as well I think. I'd say that the design is technically street legal but pretty congested none the less given the need for proper vibration/compaction etc. Me thinks it should have been a thicker wall.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[jayrod12]

It definitely makes you question the shear capacity if the moment demand is that high.

 

[JAE]

How thick is the wall?

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[dik]

and how high?

Dik

 

[Ron]

For constructability and proper consolidation of the concrete, the spacing should be about 3 times the nominal coarse aggregate size. This means that the closer the spacing, the smaller the coarse aggregate needs to be which increases the cement requirement, the cost and increases the shrinkage and corresponding cracking of the concrete.