Embedded Plate testing 3

[WARose]

Hope you will pardon a guy who is always a code or two behind (and sometimes not up on the latest research)......

Has any organization done any testing on embedded plates (for bolt groups) in concrete that you know of? Looking in Chap. 17 of ACI 318-14 (formerly Appendix D).....they still beg off that.

I'm kind of curious because I wonder if anyone has developed (as of yet) recommendations as to plate stiffness, areas to embed/not to embed, etc, etc.

 

[skeletron]

This was posted in the forum recently:

https://www.steelconstruction.info/images/e/e5/SCI_P416.pdf

Not sure if that is specifically what you're looking for. There is a sample calculation at the back. It's been interesting seeing the developments of embed plates over the last 10-15 years. The first time I had to design one, I was handed the Nelson Stud catalogue and told to figure it out. I think there was a bit of research published at that point, but not much comparing to what is in Chapter 17.

 

[WARose]

Thanks....but I am after a different animal: plates at the end of stud/bolt groups. (With pullout loads.)

 

[KootK]

- I know of no testing of this sort.

- Given where the state of the art is with anchorage design, I kinda feel as though the right answer is to never have an embed plate. Firstly it'll only be effective near the bolts unless you make it crazy stiff. Secondly, it results in sacrificing one of the concrete surfaces that you'd otherwise like to exploit in tension.

Looking in Chap. 17 of ACI 318-14 (formerly Appendix D).....they still beg off that.

- If you'd point me to the specific clause, I'd like to check that out.

HELP! I'd like your help with a thread that I was forced to move to the business issues section where it will surely be seen by next to nobody that matters to me:

http://www.eng-tips.com/viewthread.cfm?qid=456235

 

[WARose]

If you'd point me to the specific clause, I'd like to check that out.

17.1.2 This chapter applies to cast-in anchors and to post-installed expansion (torque-controlled and displacement-controlled), undercut, and adhesive anchors. Adhesive anchors shall be installed in concrete having a minimum age of 21 days at time of anchor installation. Specialty inserts, through-bolts, multiple anchors connected to a single steel plate at the embedded end of the anchors, grouted anchors, and direct anchors such as powder or pneumatic actuated nails or bolts are not included in the provisions of this chapter.

 

[Celt83]

WARose:
your condition would be the one on the right in the attached sketch? If so I don't know of any data to back up any calculation methods.

Open Source Structural Applications:

https://github.com/buddyd16/Structural-Engineering

 

[KootK]

Thanks. I paraphrase this...

...single steel plate at the embedded end of the anchors...are not included in the provisions of this chapter.

... as this:

...nobody's really planing in this sandbox so, if you want to go there, you're on your own.

I stand by my position that I can't think of anything that I might do with an embedded plate that I couldn't do better with anchors alone, even if that required some more anchors to distribute things a little better.

HELP! I'd like your help with a thread that I was forced to move to the business issues section where it will surely be seen by next to nobody that matters to me:

http://www.eng-tips.com/viewthread.cfm?qid=456235

 

[WARose]

@Celt83.....yep, it's the one on the right.

@Kootk.....I agree. You just see it on so many drawings now.....I wanted to get caught up. (If there was anything to get caught up on.)

 

[KootK]

@Kootk.....I agree. You just see it on so many drawings now.....

Yeah, you do. It is something of a time honored method. Somewhat like the embed equivalent of through bolting. I think that we can all agree that this stuff does have an undeniable, visceral appeal.



HELP! I'd like your help with a thread that I was forced to move to the business issues section where it will surely be seen by next to nobody that matters to me:

http://www.eng-tips.com/viewthread.cfm?qid=456235

 

[MIStructE_IRE]

If I’m reading your post correctly you’re essentially looking at the same thing as embedded washer/plates for column bases? Cone pull out checks?

This is covered comprehensively in the SCI Green Book Design of moment connections. I normally use Masterseries software for embedded washer plate design.

 

[Deker]

If you’re going to have a go at it I’d recommend reading over this thread (Link) and this report (Link).

 

[WARose]

If I’m reading your post correctly you’re essentially looking at the same thing as embedded washer/plates for column bases? Cone pull out checks?

Sorta/maybe......except you don't (theoretically) do these by chapter 17/Appendix D. It's a two-way punching shear check. (Being mighty careful where/how you do it.) But you need a mighty stiff plate.....not to mention good bearing stresses.

people gets lots of capacity this way because the failure plane is so large.

If you’re going to have a go at it I’d recommend reading over this thread (Link) and this report (Link).

Exactly what I am looking for. Thanks Deker!

 

[KootK]

Yes, thank you Deker! That report is a treasure and is going straight into the vault. Interestingly, to me at least, is that they specifically addressed on of my concerns.

Secondly, it results in sacrificing one of the concrete surfaces that you'd otherwise like to exploit in tension.

HELP! I'd like your help with a thread that I was forced to move to the business issues section where it will surely be seen by next to nobody that matters to me:

http://www.eng-tips.com/viewthread.cfm?qid=456235

 

[Hokie93]

The paper in Deker's link was published in the second quarter 2016 issue of Engineering Journal under the same title. The paper is available at

http://www.aisc.org

and is a free download to AISC members. It is a rare paper in Engineering Journal in that it is largely concerned with that 'other' structural material (concrete).

 

[WinelandV]

Resurrecting this thread, as I've got a request to use an embeded plate.

A couple questions:

- In the CCD method, there is a factor of (40/9). Any ideas what this is supposed to represent? Is it supposed to be a constant, or is it variable and just didn't state what it depends on?

- Is there any guidance as to how thick to make the plate? Or is just sizing it for bending based on the tensile load divided over the surface area?

 

[WARose]

- In the CCD method, there is a factor of (40/9). Any ideas what this is supposed to represent? Is it supposed to be a constant, or is it variable and just didn't state what it depends on?

I think it's a constant.

- Is there any guidance as to how thick to make the plate? Or is just sizing it for bending based on the tensile load divided over the surface area?

I think it's got to be pretty stiff. (See ACI 318-11 Sect. D.5.2.8 to give a ballpark idea.) I've always tried to make the flexural deflection comparable to the shear deflection in the plate. (THat can get pretty thick though.)

 

[WinelandV]

Thank you, WARose.

If I'm reading D5.2.8 correctly, I think this is what it's saying?

What I'm actually looking at is a plate on both ends - no anchor bolts, but angles running between the (2) plates (see below).

For trying to size the thickness of the plate, for the shear deflection, I assume you'd look at a one-way shear situation (i.e., not treating it like a plate)? The load on the embed is about 130 kips (LRFD). Also, not a seismic load, this is all wind.

Thanks in advance!

 

[WARose]

If I'm reading D5.2.8 correctly, I think this is what it's saying?

That's how I read it too. Can give you something pretty outrageous fast in the situation we are discussing. I think engineering judgement has to take over.

For trying to size the thickness of the plate, for the shear deflection, I assume you'd look at a one-way shear situation (i.e., not treating it like a plate)?

No, in the situation you are showing.....you are still going to do a two-way plate bending/shear check. You just have to separate the bending deflection from the shear deflection.

 

[WinelandV]

I've always tried to make the flexural deflection comparable to the shear deflection in the plate.

Stepping back a touch, when you say you make them comparable, are you trying to size the thickness such that the deflection computed from only shear is about the same as the deflection computed from only bending?

 

[WARose]

Stepping back a touch, when you say you make them comparable, are you trying to size the thickness such that the deflection computed from only shear is about the same as the deflection computed from only bending?

Yes. I try to keep the shear deflection and flexural def. close. (Or both very low.)