Rebar Development Length Tables
Rebar Development Length Tables
(OP)
Curious how other people handle setting up development length/splice length tables on their drawings. To set up useful tables requires building in some assumptions, for example:
- Assuming you use ACI 12.2.2 simplified equations there are requirements for clear spacing, min. clear cover, and ties/no ties.
- If you are making a table for interior elevated slabs you would normally be using 0.75" cover, do you therefore build into your table a change in equations after #6 bars, i.e. when the cover of 0.75" becomes smaller than 1 db?
- Similar questions for walls: at basement walls we show the vertical reinforcing as the outer curtain, but on shearwalls we show it inside the the horizontals - do you create two tables and account for the different typical covers for those two situations and then build that into your table? There is also the issue that portions of shearwalls may be tied/confined bars while others are not, this also may impact the development length.
- Assuming you use ACI 12.2.2 simplified equations there are requirements for clear spacing, min. clear cover, and ties/no ties.
- If you are making a table for interior elevated slabs you would normally be using 0.75" cover, do you therefore build into your table a change in equations after #6 bars, i.e. when the cover of 0.75" becomes smaller than 1 db?
- Similar questions for walls: at basement walls we show the vertical reinforcing as the outer curtain, but on shearwalls we show it inside the the horizontals - do you create two tables and account for the different typical covers for those two situations and then build that into your table? There is also the issue that portions of shearwalls may be tied/confined bars while others are not, this also may impact the development length.






RE: Rebar Development Length Tables
***Avoid unneeded complexity.
And NEVER refer the rebar detailer to ACI 318 - we see this all the time, where a designer says something like "lap splices shall conform to ACI 318)". Obviously, a rebar detailer has no way of knowing tension or compression, or any of the several values required to determine lap lengths.
RE: Rebar Development Length Tables
RE: Rebar Development Length Tables
I wasn't expecting the one table answer. We currently have only a few tables (slabs, walls, columns) with some notes about what assumptions they are based on. I recently was reviewing the drawings of another firm and saw that they have 9 different tables. At first I thought that it was excessive but after reviewing it I see that they are saving a lot of rebar by covering different conditions so I was wondering if this is typical for most firms.
RE: Rebar Development Length Tables
*Top or "other" bar
*Cover greater than two bar diameters or spacing greater than four bar diameters.
You bet it's complicated. So the fabricators almost always use the longest of the four laps. There's actually very few bars that are "other" bars (bottom bars), so it's not that extravagant.
I tried to boil it down to two lap lengths per bar on a couple projects and no one noticed, so I got lazier.
RE: Rebar Development Length Tables
You can only check lap lengths of rebars in slabs and walls, generally. It is the responsibility of the EOR to check cut sheets for lap lengths of beam and column rebars.
I would be very glad to see only one lap length per bar size in the walls and slabs, but some companies had innovative and easy to understand graphic methods of indicating more complex lap length schemes on the layout shop drawing.
RE: Rebar Development Length Tables