It is a crying shame that we have to revert to a computer program to design these blasted things when we did not have to for many many decades.
The Appendix as written is a poor excuse to a code which we are required to use. The rumor I keep hearing is that it is due to a total re-write because of the shear equations being so limited.
It will cost us all over 100 bucks to see that latest revisions.
I totally agree!! The really aggravating thing about 318 Appendix D is nobody can really point to a problem it was meant to correct.
I went to a seminar a year or two ago where a rep from ACI presented Appendix D. He was asked in the question and answer session if ACI was aware of systematic problems with post-installed anchors installed prior to Appendix D comming out. His response was 'No'.
Seems like another case of the acedemics dreaming up another way to make the practicing engineer's life a little harder for no apperant purpose.
Hear! Hear!
Besides all the extra chores that this appendix requires the engineer to do, it requires that the manufacturer's perform special testing (which very few have have done to date) for post installed anchors. You can either specify the anchors that have the testing and no equals or allow other anchors and violate the code.
I agree with the replies above that Appendix D is a solution in search of a problem. It encourages Engineers to violate the code.
It may be based on "good research" but the unintended consequences of its publication are staggering. Just look at the comments made in this forum and the extra effort being made by Hilti, and Simpson in trying to get their anchors "blessed".
The code in its present state is unweildly, unnerving, fraught never ending complexity, and just plain poorly written and documented.
I feel that there must be a better way to design anchors than to use this code. There is a marked rebellion among structural engineers in my town and I am sure that we are not alone. This is akin to the rebellion that we all saw when the IBC 2000 wind code was published. We all said, "What is the hell is this?" In articles I have read from Ghosh, there are rumblings about going back to the UBC 97 wind code or at least re-publishing the wind code provisions so people can understand it WITHOUT THE USE OF A COMPUTER PROGRAM.
The same thing has happened with this abortion known as Appendix D.
We had an ACI rep talk to our SEA luncheon and he was peppered with loud and raucous rants from structural engineers. He did the best he could but he know the gig was up. He made no headway in trying to convince the skeptical and unbelievers.
I know some of you will berate me for this post, but I venture to say that my view is more prevalent. If you use Appendix D and like it, have at it. For our design office, we have scrapped its use as being time wasteful and we are not going to buy some BS computer program either.
For me, I will use the PCI handbook until the ACI code is fixed.
can't you get around appendix D by using epoxy anchors instead of expansion anchors? Then you can just use the values published in the manuals.
I don't know how much more expensive epoxy anchors are, but if it isn't a consideration, just use the epoxy anchors.
I noticed that App. D is hard to follow, especially when it comes to post-installed anchors. But the ACI-05 Appendix D is much revised and easier to follow than in the 02 edition (I am not saying it is the best ever). The equations have not really changed but the commentary and explainations are much improved.
For everyone's information in the 2006 Nov.-Dec. issue of the ACI Structural Journal there was an article for Design of Adhesive anchors in concrete. There is the possiblity that this could find its way into future editions of 318 and than things would get crazy.
Appendix D may be based on good research. My problem with it is (other than the fact that it is so poorly organized and written as to be almost unreadable)that it addresses a problem that never existed in the real world.
Prior to Appendix D, post installed anchors had such a high factor of saftey (FS = 3.75 in seem to recall), that there was never a problem with them in real life. Niether I, nor anyone in my office, can remember seeing a problem with post installed anchors due to cracked concrete.
MinorChord: I agree 100%!!! Most engineers I know are just basically ignoring it Appendix D. Thats not how codes are supposed to work, but when a code body hauls off and does something as bad as Appendix D, what do they really expect to happen?
StucturalEIT: Unfortunatley, epoxy anchors are considerablly more expensive that expansion anchors. By a focator of 2 or so. I've taken to using the RedHead Large Diamter Tapcon, Simpson Titen HD, etc in place of expansion anchors where I can. They are about the same cost (installed), but have Appendix D IBCO approval.
There are only a few products that are approved by ICC for use with App. D. There are no screw anchors or adhesive anchors that have approval for App. D.
Hilti KB TZ (ICC ESR 1917) Cracked and Uncracked Concrete
Hilti HSL-3 (ICC ESR 1545) C & UC
Hilti HDA (ICC ESR 1546) C & UC
Simpson Strong-Bolt (ICC ESR 1771) C & UC
USP DUC Undercut Anchor (ICC ESR 1970) C & UC
Red Head Trubolt (ICC ESR 2251) Uncracked concrete only
There are no other products that meet this code currently. All adhesive and screw anchor products have gotten a one year extension to meet these new requirements but are limited in their use in seismic areas. On January 1st, 2008, if the current screw and adhesive anchors do not have their testing completed they will loose their ICC report as well. Although there is a little paragraph in ACI 318 about adhesive anchors being ok for now, this will not be the case after this date. The design equations for adhesive anchors will not be in ACI 318 until the 2011 version, but will be presented in AC 308 (Acceptance Criteria for Adhesive Anchors in Concrete). Please read this from ICC for their story.
