Post-installed anchors
Post-installed anchors
(OP)
I have a general question for everyone regarding post-installed anchors. We just had a brief discussion at my office regarding this, but I wanted to get others opinions.
When designing post installed anchors, do you generally use the capcaities provided in the Hilti/Powers manual or do you follow Apendix D of ACI 318?
It was mentioned in the discussion this morning that the Hilti/Powers manuals are vastly under-conservative when compared with values obtained using Appendix D of ACI 318. Hilti apparently has software called PROFUS (I think I spelled that correctly), which takes Appendix D into account when arriving at capacities.
I have used the capacities in the manuals and applied my own factor of safety, usually around 10 (depending on the application) for critical components.
How do all of you approach this?
When designing post installed anchors, do you generally use the capcaities provided in the Hilti/Powers manual or do you follow Apendix D of ACI 318?
It was mentioned in the discussion this morning that the Hilti/Powers manuals are vastly under-conservative when compared with values obtained using Appendix D of ACI 318. Hilti apparently has software called PROFUS (I think I spelled that correctly), which takes Appendix D into account when arriving at capacities.
I have used the capacities in the manuals and applied my own factor of safety, usually around 10 (depending on the application) for critical components.
How do all of you approach this?
RE: Post-installed anchors
When using Appendix D, you have to use the coefficients that the manufacturers give you, but there aren't too many anchors out there that fall into this category.
I use Appendix D, for anchor bolts and headed studs. I use the manufacturer catalogs/programs for the others.
RE: Post-installed anchors
With the Appendix D design model, you must consider cracked concrete in most cases. As such, only a few post installed anchors are acceptable for use.
Simpson has seminars to help explain (the guy in GA really does provide a non biased technical presentation), ACI has seminars and so on. It really does seem to be a big step from what has been the status quo.
Expect some changes.
Good luck!
Daniel
RE: Post-installed anchors
I agree with rgerk to use Appendix D for embedded bolts and test report values for proprietary post installed anchors (expansion anchor, adhesive anchor, shot-pin, screw anchor, etc).
RE: Post-installed anchors
RE: Post-installed anchors
RE: Post-installed anchors
RE: Post-installed anchors
RE: Post-installed anchors
In Profis also, there's one option is to design using ETAG.
RE: Post-installed anchors
Dik
RE: Post-installed anchors
To use the proprietary post-installed fasteners such as Hilti or Simpson, the post-installed fasteners have to be qualified under a testing procedure which is stated in ACI 318 Appendix D. There were problems with the original testing procedure in ACI 318-02. None of the manufacturers tested any on their products because they did not want to waste their time and money, therefore none of their porducts were qualified to use in ACI 318-02. ACI has since revised the testing procedures for post-installed anchors and anchor manufacuturers have started testing their anchors to qualify them for use in ACI 318-05. The manufacturer has to test the anchors and submit design information for the anchors. As of today, Hilti has several anchor qualified for Appendix D and Simpson has a couple. I am unaware of any others. The new Hilti 2006 catalog has the design values for use in ACI 318-05 Appendix D for their anchor which are qualified. Contact Hilti or Simpson representatives. I have a good relation with the Hilti rep in Pittsburgh and he is very helpful. I have an entire design binder from them.
RE: Post-installed anchors
RE: Post-installed anchors
It will take some time before the post-installed anchor companies get all the kinks worked out. I personally think App D is highly flawed especially with regard to allowable shear. App D was rushed into publication without thought to the unintended consequences and is really a "work in progress." I expect to big revisions to App D over time.
For anchors under seismic or wind loading, I use App D and only specify headed bolts.