Anchor bolt embedment depth 1

[IFRs]

This is probably a dumb question, but is there a simple rational method to determine the required depth of embedment for a single headed anchor bolt in normal reinforced concrete 24" thick that is nowhere near the edge or another anchor? If I use a 45 degree cone, the depth comes out pretty shallow but if I look at other designs they use 2 feet or more. I'm looking to design either cast in place or Hilti type for this application. The Hilti type is right from their catalog, it's the cast in place that I am struggling with. I have 1 1/2" bolts needing to develop 32000 pounds.

 

[ishvaaag]

Normally one would follow a code, or follow a guide like a special publication on anchors to concrete by ACI. ACI 349, UBC 94 and I suppose also current IBC should have something about. Will try to post some pdf on the issue maybe tomorrow.

 

[ishvaaag]

The Manual of Concrete Practice MCP-05 has the document

ACI 349.2R-97
(Reapproved 2002)
Embedment Design Examples
Reported by ACI Committee 349

PART A—Examples: Ductile single embedded
element in semi-in nite concrete. . . .p. 349.2R-3
Example A1 Single stud, tension only as

 

[ishvaaag]

Likely if by such estimate you are going too long into the concrete you should spare effort and directly investigate the proprietary anchor bolt designs, part of their success is of being shorter.

 

[IFRs]

I have looked at the Hilti type epoxy anchors. They seem to develop a true cone failure. However, the customer wants cast in place anchors. Apparently the cast in place type do not break out a cone the same way as the epoxy type and I can't just put a plate on the bottom of the anchor and expect a cone failure. I could easily calculate the surface area of the cone and apply sqrt(Fc) for shear strength and determine a required embedment depth. Sigh. Apparently it is not that easy and there are no rules of thumb for a conservative yet adequate design.

 

[ishvaaag]

And these other mathcad worksheets (printouts)

 

[ishvaaag]

Other

 

[ishvaaag]

And yet another as if masonry

 

[IFRs]

ishvaaag -Thanks for the help! I have MathCAD - are the worksheets available?

 

[sdz]

IFRs
The answer is Yes and it is in ACI318 Appendix D. This method, the concrete capacity design (CCD) method is based on extensive research and supersedes and is much better the old method using 45 degree cones.

The anchors should be designed to yield before concrete failure to ensure ductility.

 

[IFRs]

Which edition of ACI318 has the "good" APpendix D? I fear mine might be too old (I can check when I get back to the office Mondsy)

 

[Ron]

ACI 318-02 or later.

 

[ishvaaag]

They were made available at the Collaboratory site of Mathcad 2000. Since PTC took over Mathsoft, the software house that developed Mathcad, the site seems not to be available but for those having a license of Mathcad (the website could be open before from within Mathcad and any ordinary browser)...

I wil try to place a copy of this set of worksheets at some file repository and then pass the link. Sorry, I didn't looked again this thread these days.

 

[ishvaaag]

Have zipped the folder with the worksheets (1 of them seems to be a variant for whatever the reason). I have not saved after checking the worksheets since my current setup at this computer is messing a square character where a · point character multiplication. This shouldn't be a problem in yours, but setting "view multiplication as.." doesn't entirely function in my case.