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RE: ICBO ER Anchor Bolt Values

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Bob Shilling wrote:

> I've been unsubbed from this list for a while, and have missed 
> anydiscussion which may have taken place on this topic. I have 
> unsuccesfully searched the archives, also.
> 
> Anyway, I'm sure everyone is aware that the ICBO reports have, over
> the 
> last couple of years, added a comment sort of like "The use of these 
> anchors to resist wind and seismic loads is beyond the scope of this 
> report." This of course, effectively removes ICPO "approval" of the 
> anchors. I think by now that they have pretty much disavowed (shades
> of 
> the IMF) use of all drilled-in, mechanical anchors, but not the
> chemical 
> ones.
> 
> I have several questions that I am hoping some of the list members may
> be 
> able to help with.
> 
> 1. Why?
> 
> 2. I have always understood that ICBO "approval" is required for code 
> compliance, however I can't find where it says this in the code. If my
> 
> assumption is correct, can anyone quote me chapter and verse?
> 
> 3. What are y'all using instead?
> 
Following is a re-post of part of a thread that occured several months
back, including my reply.  Just to summarize:

1.  An ICBO report is an evaluation report, not an approval.  Although
many engineers and building officials in UBC areas choose to use them,
there is definitley no code requirement to do so.
2.  ICBO has not in any fashion "disavowed" the use of mechancial
anchors.  An acceptance criteria has finally been established, but a few
of the requirements have changed, and most manufacturers are in a
"retest" mode.  This is why (to my knowledge) no new reports have been
issued on mechanical anchors "allowing" use to resist seismic loads.

Please read on if you're interested

Chris Gill
gillchr(--nospam--at)us.hilti.com

---------

IMHO, the ICBO ES reports provide some information about applications
and application limitations, however, they are no substitute for good
engineering judgement.   Nor do they cover an engineer from exposure to
liability, as the disclaimers that are plastered all over the reports
indicate.  The reports are entitled "Evaluation Reports" because they
are intended the evaluate the use of a specific product in lieu of the
"code item" (in this place a cast-in-place anchor.)  This does not mean
that you should do what the ICBO report tells you to do (or not do what
it does not tell you to do) in lieu of good judgement or engineering
principles..

	This leads me to the second point about mechanical anchors.  In
the summer of 1996, ICBO issued a supplements to all holders of
Evaluation Reports on mechanical anchors, stating "Use of anchors in
resisting earthquake or wind loads is beyond the scope of this report."
The post from Mr. Tang states "...during cyclic loading conditions,they
have not proven themselves worthwhile."  It is a big leap from 'beyond
the scope of this report' to being not 'worthwhile."  In fact, what
happened is that ICBO ES realized that they had no criteria to use in
evaluating seismic performance.  In fact,  we asked for a clarification
from ICBO ES on this issue, and we received a letter saying (in so many
words) that they had no evidence that there was a problem, and no reason
to believe that there would be a problem (in seismic events),  just that
there was no criteria to evaluate suitability.  (If you would like a
copy of this letter, please E-Mail me directly.)

	Please also keep in mind that "all mechanical anchors are not
created equal."  I have seen generalized statements in this thread
stating that 'mechanical anchors are no good for tension' or that 'wedge
anchors slip too much.'  This may or may not be true for a given
product.  (On the other hand, I agree with the statements that expansion
anchors are generally not good in close edge distance situuations.)
There are several types of mechanical anchors of various quality levels,
including Torque Controlled and Displacement Controlled.  Thanks to Tom
Chiu for pointing out that the Hilti HSL is different from the run of
the mill "wedge anchor."  We ran an extensive test program at the
University of Texas including 2 million cycle fatigue, along with hefty
seismic and impact loading conditions, and got great results.  (If
anyone would like a copy of the report, please E-Mail me.)  And, the
contractors like them because they are as easy to put in as a wedge
anchor.   ICBO ES did not accept the UT testing, of course, because
there was no evaluation criteria in place. 

	One last note on mechanical anchors and ICBO ES:  Any
manufacturer who has a report dated within the past few years has tested
their product and submitted data in accordance with ICBO ES Acceptance
Criteria 01.  This means that they have tension tested the product with
only 20% of the recommended torque and achieved 80% of the "full torque"
value.  It also means, among other things that they met the displacement
criteria set forth in AC 01.  Also, Edge Distance and Multiple Anchor
groups are tested, etc, etc.  IF you need a copy of AC 01, ICBO ES would
probably give you one.  The final piece of the puzzle was completed last
fall when the Acceptance Criteria for the seismic portion was adopted.
After some back-and-forth on the displacement limits, manufacturers
began testing later in the fall and many have already submitted the
results to ICBO ES.  We are awaiting a new supplement on the Kwik Bolt
II and HSL anchors, clarifying the seismic issue.

	If anyone actually read this whole thing, thanks for listening.

	Chris Gill
	gillchr(--nospam--at)us.hilti.com




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