Splice length reduction using hooked bars
Splice length reduction using hooked bars
(OP)
Hi,
I am wondering if anybody knows whether or not it is permitted to use hooks for a reduction in lap splice length.
ACI 318-14 Cl. 25.5.2. talks about lap splice lengths for deformed bars in tension, and calculates it using the development length, but the development length mentioned pertains only to straight deformed bars. I would like to have hooks on the ends of both rebar involved in the splice to reduce the splice length.
Any experience/references on this would be greatly appreciated.
Thanks!
I am wondering if anybody knows whether or not it is permitted to use hooks for a reduction in lap splice length.
ACI 318-14 Cl. 25.5.2. talks about lap splice lengths for deformed bars in tension, and calculates it using the development length, but the development length mentioned pertains only to straight deformed bars. I would like to have hooks on the ends of both rebar involved in the splice to reduce the splice length.
Any experience/references on this would be greatly appreciated.
Thanks!






RE: Splice length reduction using hooked bars
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RE: Splice length reduction using hooked bars
Dik
RE: Splice length reduction using hooked bars
@dik Do you know where I can find/buy past publications of ACI? Google isn't being too helpful.
RE: Splice length reduction using hooked bars
https://ctr.utexas.edu/wp-content/uploads/pubs/0_1...
RE: Splice length reduction using hooked bars
RE: Splice length reduction using hooked bars
First, hooks only work in tension (so no lateral or reversal of forces).
Other Code limits notwithstanding, the orientation of the hooks would be important to avoid doubling the splitting force in the concrete created by the hooks. Two hooks occupying the same concrete will increase the crushing and splitting forces in the concrete. (Ref to ACI 318-14 R25.4.3.3). Confinement and congestion will be a issues. The overlap in a typical case lap length vs typical case ldh would be reduced from 42 inches to 17 inches. 14 inches of additional bar would be required for the bend and the required extension on a 180 bend, on each side. The savings in physical bar length would be no more than about 4.9 lbs per lap for #8 (trivial when compared to the added labor to bend, bundle, transport, handle, and precisely place bent bars). Obviously the length of the lap is not much of an issue if you are lapping bars.
RE: Splice length reduction using hooked bars
Dik
RE: Splice length reduction using hooked bars
- My understanding is that the 1.3 factor on splicing is mostly about the possibility of reduced bond development where the bars might be in physical contact with one another. Rationally, bars developed via hooking would have less of that problem and therefore, all other things being equal, I'd expect them to perform better.
- In my opinion, this kind of thing largely defies rational analysis and testing must be held as the gold standard.
If it was a zillion #4 bars at 12" o/c, I'd be willing to let it go. If it were 3-#8, not a chance.
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: Splice length reduction using hooked bars
Part extract from ACI 318-63:
'Part IV-A' is working stress:
'Part IV-B' is ultimate strength:
You can purchase historical ACI codes from 1908 to 2005 on a USB thumb drive here: Link
RE: Splice length reduction using hooked bars
Dik
RE: Splice length reduction using hooked bars
RE: Splice length reduction using hooked bars
RE: Splice length reduction using hooked bars
Toby
RE: Splice length reduction using hooked bars
I am going to just tell them to install terminators on either end to due to lack of research on hooks used in lap splices.
RE: Splice length reduction using hooked bars
1) Up your f'c to lower your lap length.
2) Mechanically couple some extensions.
3) Weld some extensions.
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.