ACI 318 Appendix D 5

[ntpe]

Are you using Appendix D for anchor bolt design? This also applies to wedge type anchors, but as far as I can tell Hilti, Rawl, Ramset ect. have not done enough testing to meet Appendix D with all of their bolts. Right now, Appendix D does not apply to threaded fasteners or advesive anchors, but this will change. How are you dealing with this?

 

[JedClampett]

I'm doing what I've always done and look up the allowable load in a readily available ICBO report.
I really think that ACI went overboard in this area. I guess it's nice to have an analytical method of getting allowable loads for embedded items, but wow, the way they came up with is real tedious.

 

[whyun]

Agree with JedClampett. Expansion anchors and epoxy anchors are not as "predictable" as an embeded bolt due to manufacturers' variations in the shape of the wedges for expansion bolts and chemical content for epoxies. Only way to determine a comfortable level of design forces are by testing.

 

[JStephen]

As I recall, the method is limited to 2" maximum bolts and 30" or so of depth, which is somewhat limiting.

See my earlier post where I was trying to figure out how to handle a circular bolt pattern. There are different approaches, but the sum of it all is that the Appendix just wasn't intended for circular bolt patterns, and appears very awkward to apply in these cases.

 

[UcfSE]

The ACI has a new publication, 355.2-04, for post-installed anchors. I use the manufacturer's published values currently for expansion bolts, epoxy bolts and pdf's. I do verify these with ICBO reports also. For c.i.p anchors I use the App D. The 318-05 supposedly is updated to provide design values for post-installed anchors. You can, if you choose, use the method in the PCI Manual.

 

[ntpe]

I have spoken with several of the companies that manufacture wedge and undercut anchors and they tell me that, with the exception of the HILTI undercut anchor, they have not completed the testing required per Appendix D. As for the ICBO reports, I was told that by several manufacturers that I spoke with that there were no ICBO reports that comply with Appendix D. As for using the allowable loads currently published by the manufacture, these are no longer valid under ACI or IBC.

 

[whyun]

Ultimately, it is up to the local building departments or jurisdiction to allow or disallow such use. For example, City of Los Angeles publishes LARR (Los Angeles Research Report) with their own modifications (typically reduction in ICBO listed values). Other jurisdictions take the ICBO at face value. Yet another jurisdiction may not be sophisticated enough to require either way.

Find out what the appropriate building officials require for the project at hand.

 

[JAE]

I spoke with both Simpson and Hilti personnel. Simpson guy made the following statment:

[red]The Strong-Bolt is a new wedge anchor that has been specifically designed and tested for use with Appendix D of ACI 318-02. If you are unfamiliar with Appendix D, I urge you to read it along with section 1913 of the 2003 IBC. The 2003 IBC is requiring that all expansion and undercut anchors be designed per ACI 318 Appendix D. This appendix is requiring that all expansion and undercut anchors be prequalifed before they can be used with the strength design equations found in Appendix D. Unfortunately, wedge anchors that have been used in the past (Simpson's Wedge-All, Hilti's Kwik-Bolt II & 3, etc.) will be unable to pass the qualifying tests of ACI 355.2 and will not be allowed to resist structural loads per the 2003 IBC. Consequently, Simpson has developed the Strong-Bolt to give engineers the ability to still specify and use expansion anchors for structural applications.

There are many other issues that go along with Appendix D, so I urge you to familiarize yourself with this section of the code if you haven't already. If you have any questions regarding Appendix D, please feel free to contact me.[/red]

Then, I got this response from Hilti:

[blue]Indeed it is important to be clear in explaining the situation facing the design of anchors under the 2003 International Building Code.

The 2003 IBC makes reference to ACI 318-02 Appendix D for the design of anchorage to concrete. This section of the code uses an ultimate strength design approach to address the design of cast in and post installed mechanical anchors. In order to qualify a post installed mechanical anchor to be used with the design method detailed in Appendix D of ACI 318-02, the anchor must undergo test procedures of the type described in ACI 355.2. ACI 355.2 is comprised of reference, reliability, and service condition tests that assess the performance of the anchor in a variety of conditions. This may or may not include testing of anchors in cracked concrete, depending on the scope of the assessment desired/required.

As originally drafted, ACI 355.2-01 contained some provisions that would have made the qualification of expansion anchors difficult if not impossible. This situation was remedied in the short term by the issuance of AC193 which incorporated the necessary fixes to make ACI 355.2 a workable standard. Note that these changes were simultaneously processed through ACI, and that the most recent edition of ACI 355.2 (-04) has implemented many of the necessary corrections/adjustments.

To summarize there are a couple of statements that I wanted to clarify:

1) As far as we are aware, Hilti is currently the only anchor manufacturer with ESR reports issued under AC193 for the 2003 IBC. (ESR 1545 for the Hilti HSL-3 Heavy Duty Expansion Sleeve Anchor, and ESR 1546 is for the Hilti HDA Undercut Anchor, each contain the requisite information for anchor design in accordance with ACI 318 Appendix D and hence the 2003 IBC.) We expect this situation to change in the next 12-18 months as anchor manufacturers begin to re-orient their product lineup and testing to the new standards.

2) We are aware that Simpson has distributed design information for their Simpson Strong Tie Strong Bolt. Simpson represents this data is in conformance with AC193. However, it is our understanding there is currently no ESR report issued for this anchor.

3) Lastly, relating to a specific manufacturer's comment:

"Unfortunately, wedge anchors that have been used in the past (Simpson's Wedge-All, Hilti's Kwik-Bolt II & 3, etc.) will be unable to pass the qualifying tests of ACI 355.2 and will not be allowed to resist structural loads per the 2003 IBC. "

This is an unfortunate misconception regarding the ACI 355.2/AC193 qualification standard. While it is true that many existing anchor types may not be able to qualify under the cracked concrete provisions of the standard, and will therefore be limited to non-seismic loading, we expect many of Hilti's current structural post-installed anchor types would be capable of qualifying at some level under AC193. Hilti is in the process of testing several of their existing products and new anchoring products in the upcoming months in order to provide a broader range of anchoring solutions to our customers and structural engineers. Robert will be providing you with this design information as it becomes available.

I have attached a copy of AC 193 and ESR-1545 and ESR-1546 for your review. You can also download them from the ICC website at:

http://www.icc-es.org/reports/index.cfm?search=search

For now, these 2 anchors can be specified in order to comply with the 2003 IBC. Although the Hilti HSL-3 and Hilti HDA are the only post installed concrete anchors with an IBC 2003 approval, all medium and heavy duty mechanical and adhesive anchors from Hilti are approved under the IBC 2000 code.[/blue]


Hope these help.

 

[WillisV]

So at the stroke of midnight when your state adopts IBC 2003 all of the current expansion anchors in that state are going to fail simultaniously right???

 

[YKalaf]

There is one thing that gets me confused when using Hilti's load capacity specification for their not ACI 355.2 complaint anchors, and that is the lack of technical information-codes desing relation and the prescence of certain ambigueties. Example: they list ultimate and allowable capacity for their anchor, but states that the capacity modificator factors shall be aplied to the allowable capacity listed. This ambiguety as to which capacity to use leaves me with the costly option of being overlyconservative.