How to Calculate Development Length of Concrete Reinforcing - 4 Examples Using ACI 318-14

Team Kestava back with a lesson on calculating development lengths of concrete reinforcing. the lesson includes 4 examples using the ACI 318-14 design manual. The 4 examples are
1 - rebar in tension
2 - rebar with hooks in tension
3 - rebar with terminator heads in tension
4 - rebar in compression
Full design examples with live navigation through the ACI 318-14 manual.
#kestava #teamkestava #concretedesign

[@damianokon6209]

A simple way of remembering the diameter of a bar is simply taking the bar size and multiplying it by that number of 1/8" intervals. For example 4*(1/8") = 4/8" = 1/2" = 0.5 inch which is the diameter of a #4 bar.

[@Kestava_Engineering]

this is SO good! I didnt make this connection!

[@davidr2943]

Close to true, but not quite. Up to #8 bar, this 1/8" pattern is the case, but beyond that I noticed that the bar size started varying from that pattern. For example, with the "eighth inch rule" as you describe, #9 bar would be with nominal diameter of 9/8" = 1.125" , but it is actually with nominal diameter of 1.128". Another example: Rebar size of #11 would be with nominal diameter of 1.41" and not 1.375" per the "eighth inch rule". Granted, it seems that if you were to assume 1/8" every time, you would be conservative for area steel (like for bending moment capacity), but I would suggest to make sure to use a chart for anything larger than #8 bar for anything involving development lengths and such.

[@KAMILWIJDAN]

you are great Sir . i respect all your efforts . the way you teach is amazing Thank you soo much

[@Kestava_Engineering]

thank you!

[@structureclass2829]

Wouldn't ACI 318-19 be the most current code? I imagine it might be good to use ACI 318-14 for the video anyhow because PE/SE exam still reference it. I got a pdf version the 318-19 through the library genesis website I believe. I think all the code references/sections are the same, but ACI modified some equations slightly and added factors for higher grade reinforcement (Grade 80 and Grade 100).

[@Kestava_Engineering]

Hi Logan, i knew they were working on 318-19 but was not aware that it had come out! And you are spot on about using 318-14 for the exams. the exams still specify 318-14. for everyone out there - always make sure you check what codes are being referenced for the exam of the year you take it! the last time ACI updated, they completely turned the code chapters around!

[@syedmubarak8795]

Nice class bro keep it up and we will support u for making more classes like this

[@Kestava_Engineering]

@@syedmubarak8795 thank you! i will work hard to keep producing content that furthers your engineering career!

[@syedmubarak8795]

@@Kestava_Engineering thanks brother

[@signaltouch7413]

you're amazing , thank you

[@Kestava_Engineering]

You are!

[@bagusbudi3018]

Where is the proper posisition of the development length for concrete column & beam according to the aci code? And is there an explanation regarding the development lenght position.

[@dontransue9843]

Table 25.4.2.4 shows that a number 6 and smaller bars use a coeff in the equation of a 0.8; What is this for here? Did we already account for this prior to using this table?

[@nwey6151]

Can this formula be used for prestressed concrete?

[@betaleducation6060]

In the first one (ld of deformed bars and wires in tension), the lap spliced bars are in contact with one another and you are still taking the first case. Why is that?

[@ehabaltimimi660]

Yes, why case 1?

[@xinglan9129]

@@ehabaltimimi660 I think the first example should use Other Case (case 2) to calculate the development length because rebars are in contact with each other.

[@joseh7612]

What do you mean by first case?

[@joseh7612]

@@xinglan9129 what’s case2?

[@titi0xiaotian]

I think the explanation will be if they are in contact with each other, we can take them as one with very good cohesion with the surrounding concrete, you don’t have an issue with the “spacing” But if they are not, then we need to talk about the spacing as if it is less than diameter then the space is not sufficient for the aggregate to fit in, then you will get voids then it goes the other case scenario.