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Horz Rebar Splice in Pit Wall

Horz Rebar Splice in Pit Wall

Horz Rebar Splice in Pit Wall

(OP)
I've designed some large pits in the ground.

They are 40' long and 15' wide and 16' deep. Walls are 20" thick.

That said, I received the rebar shops today and they have the horizontal bars of the pit walls spliced at the midpoint of the 40' long wall. Its a lap splice. The splices are not staggered. They are #6 bars.

Given this, I feel like these splices ought to be staggered, but can't find a code provision requiring that.

Have you guys run across this before? If so, what's your opinion of the splice of the continuous horz bars? Should splices be staggered?

RE: Horz Rebar Splice in Pit Wall

1) For a system like this, I'd expect your walls to be spanning vertically (cantilever) along the 40' side near center. As such, it would be the vertical bars doing the flexural work and the splices in the horizontal bars wouldn't matter much as those would just be distribution / crack control / temperature and shrinkage.

2) If your 40' wall is spanning horizontally, that changes things a bit. There is still no ACI provision that I know of that requires staggering but, in the 318 commentary section, they do recommend placing lap splices at locates of reduced flexural stress. Non-mandatory.

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.

RE: Horz Rebar Splice in Pit Wall

ACI would require Class B splices (1.3 x development length) if you don't stagger vs. a Class A splice (1.0 x dev. length) if you stagger AND your unity is less than 0.5.
See ACI Section 12.15.2 (in ACI 318-11)

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RE: Horz Rebar Splice in Pit Wall

(OP)
It would seem to me that, in 12.2.4 (a), since these horizontal bars are in a wall that is 16' tall....that more than 12" of fresh concrete will be below the bars, the factor for that, per 12.2.4 (a) would be 1.3, to be used in the development length calculation.

Additionally, conservatively, even though I am going to stagger the splices, I would still use class B splice, to make the lap length splice 1.3 x's the development length.

All that being said, I don't like all of the splices lining up....even though I do not see a code provision that prohibits it. So I am probably going to require staggering of the splices as well.

I don't want to be overly conservative, but at the same time, I want to do what is right.

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