What is the cut off point to use Appendix D Ch. 17 ACI 318-14 (18" or 24")??

[chorner26]

If i was designing a 24"sq x 48" tall light pole base of 3000 psi concrete,
At which point can it ignoring appendix d and just use reinforced concrete design with tension reinforcement and and shear stirrups.
IS is 18" or 24" inches or is there a specific code section that I can point to on how to fully develop the bars and not calc for appendix d?

Let's say I have 20 foot moment arm and lateral load on 500# at the top.

 

[KootK]

In my opinion, you always have the option of using reinforced concrete design principles regardless of the anchor depth. AppD is just one of the tools available to you if you wish to use it. Granted, at very shallow anchor depths, you're likely to struggle to make reinforced concrete design principles calc out is you're doing it properly.

I suspect that what your thinking of is the business where the testing that led to the development of AppD did not consider anchors deeper than 24" and, thus, AppD's applicability for anchors deeper than that may be questioned.

 

[r13]

You can get away with App. D, if you use deep foundation, or spread footing, and utilize the vertical rebars as fastener. But practically it is not recommended.

 

[canwesteng]

Just make sure the tension from the bars has somewhere to go (i.e don't stop the bars and call it good), and that they are properly developed in the concrete.

 

[chorner26]

Interesting point is I sat through the latest ACI seminar to update us on the new book.
I asked ACI rep and the PHD who was teaching the lecture about a shear lug and base plate design in to a reinforced concrete sonotube column and he looked at me with a blank stare.
I asked him about App D vs Standard Reinforced concrete.
He had no answer.
Thus KootK, I believe your answer to be accurate.
In that I will just always justify using reinforced concrete design and make a plan checker tell me I'm wrong for doing so.

Last questions is, is there any sort of guidance for threaded rods for design as tensile reinforcement in reinforced concrete. (anybody know of a section.?

 

[r13]

I asked ACI rep and the PHD who was teaching the lecture about a shear lug and base plate design in to a reinforced concrete sonotube column and he looked at me with a blank stare.

I don't know why the lecturer reacted that way, tired maybe. I think shear/tension transfer between anchor bolt and reinforcing steel is covered in App. D. Otherwise, how you design anchorage in the pedestal of spread footing then?

 

[ATSE]

Re: shear lugs, most building designers are not too familiar with how to calc capacity.
Base plate shear lugs (for horiz shear) are not well codified yet.
Both AISC Design Guide 1 (2nd Ed) and ACI 349-06 have some discussion.

 

[Agent666]

To add to ATSE comment on shear lugs, getting off topic, but ACI318-19 has an entire section on the design of these now in clause 17.11.

 

[r13]

I missed the "shear lug" in the sentence. In pier type structure? I use App. D to determine anchor length, and concrete and anchorage geometry/layout details, which weren't covered in the main code body.

 

[r13]

App. D is a headache at times, but it is also a long sought gift. I remember the days when using USD for concrete design, but ended up using ASD for embedment design. A lot of shear cones had drawn... but uncertainty remained very high due to lack of guidance, only to be covered by sky high safety factors that made design very difficult.

 

[STrctPono]

chorner26, if you are talking about post installed reinforcing dowel bars then you are correct that you can ignore Appendix D and design using traditional reinforced concrete design principals. Your development calculations will be based on the arrangement of your dowel bars and the performance data provided by the adhesive manufacturer. You do not need to use Appendix D for post installed rebar.

 

[r13]

Adhesive Anchors
This anchor type was accepted by ACI 318-11 in a three-part acceptance format...

...For states and municipalities using the 2012 International Building Code (IBC 2012), IBC 2012 has adopted ACI 318-11 and ACI 355.4-11. However, the U.S. is under a stepped phase-in period for adoption of the design and qualification of adhesive anchors.

As of 15 January 2014, the following actions were taken:

All adhesive anchor Evaluation Service Reports (ESR) will reference ACI 318-11, Appendix D. This includes the design provisions for bond strength and concrete breakout.
ESR’s also carry forth several of the code provisions for qualified installation personnel and inspection.
As of 15 January 2015, the following will be required:

Testing referenced in the ESR’s by the manufacturers will conform to the revised AC308, which is essentially ACI 355.4-11.
There are many more nuances to the IBC 2012 and ACI codes referenced and the phase-in situation. Reference should be made to a paper by Hoermann-Gast (2013) for additional information.

 

[r13]

The new structural building code (ACI 2014) will be re-organized based on member type. Appendix D will now formally be placed in the body of the Code as Chapter 17. But unlike other chapters in the re-organized Code, Chapter 17 essentially remained an untouched clone of Appendix D. This was a conscientious decision by the 318 Code Committee at the beginning of the reorganization work, because: (1) the Appendix D anchor design provisions are still “relatively new” and (2) there was a desire to keep things the same, as the design profession and university classrooms are just getting familiar with the provisions. The next code cycle will contemplate further additions and layout reorganization.