Issued: February 2, 2009
Canvass Date: March 10, 2009
ACI 318-B Ballot CB09B-01 Summary (March 11, 2009)
Name
CB004
CB008
CB001
Anderson
Browning
Cagley
Cook
Darwin
Fiorato
French
Gustafson
Jirsa
Kopczynski
Lobo
Lutz
Meinheit
Mize
Paulson
Tolles
Wyllie
Y/C
Y
Y/C
Y
Y
Y
Y
Y
Y
Y/C
Y
Y
Y
Y
Y
Y/C
N
N
Y/C
Y
N
Y
Y
Y
N
Y
N
Y
Y
Y
Y
Y
Y
Y
Y/C
N
Y
Y
N
Y
Y
Y
Y
N
Y/C
Y
Y
N
Y
N
N
Total Y
12
13
8
Total Y/C
4
1
2
Total N
1
3
7
Total A or 0
0
0
1
Also received comments by Ghali on CB013
o
o
o
o
o
o
o
o
o
CB013
CB016
CB100
CB106
CB116
N
Y
Y
Y
N
N
N
N
Y
Y/C
A
N
Y/C
Y
Y
Y/C
N
6
3
7
1
Y
Y
Y
Y
Y
N
Y/C
Y
Y/C
Y
Y
Y/C
Y
Y
Y/C
Y
Y
12
4
1
0
N
Y
Y
N
N
N
Y/C
Y/C
N
N
A
N
Y/C
Y
N
A
N
3
3
9
2
N
A
Y
N
Y
N
N
A
Y
Y
Y
Y
N
Y
Y/C
Y/C
N
7
2
6
2
N
Y
Y
Y
Y
Y/C
Y
Y
Y
Y
Y
Y/C
N
Y
Y/C
Y
N
11
3
3
0
CB001 – Change bar size factor, s, for No. 6 bars (Darwin)1
CB004 – Revise 3.5.3.1, 3.5.3.2, R.3.5.3.1 and R.3.5.3.2 (Gustafson)
CB008 – Lightweight concrete factor for bond (Browning)
CB013 – Clarification of existing provisions related to headed reinforcement (Paulson)
CB016 – Add zinc and epoxy dual-coated reinforcing bars to the code (Gustafson)
CB100 – Design requirements for adhesive anchors (Silva, Eligehausen, Cook)
CB106 – Bi-directional shear and shear-tension interaction (Lutz)
CB116 – Remove reference to “prism” in Appendix D (French)
Informational item – (Lutz)
1
Name in parentheses indicates author of code proposal
ACI 318-B Ballot CB09B-01 Summary (March 11, 2009)
o
Last Name Submittal #
Page
#
Line
#
Vote:
Y
Y/C
N1
A
Y
Comments
Clearly the s = 1.0 for No. 6 bars is needed to remove the
unconservative calculation of ld
Meinheit
CB001
Cook
CB001
Fiorato
CB001
1
0
Jirsa
CB001
1
0
Anderson
CB001
2
27
Y/C For the second column heading, we indicate deformed wires.
Is this for all deformed wires? If so, please add the word “all”
to before deformed wires. Alternately, we know the #5 bar is
a W31 and a #6 bar is a W44 wire size. Do we need to
indicate a similar wire distinction because we are changing
the bar size limits from a #6 to a #5?
Anderson
CB001
3
1
Y/C See above comment
Anderson
CB001
3
11
Y/C See above comment
French
CB001
3
22
Y/C Lines 22-29. Consider changing reason statement in
commentary. It was my understanding that bars smaller than
No. 6 also indicated that the small-bar factor was not
appropriate, but the rationale for not changing the
requirement was because the smaller size bars were typically
used in situations like slabs or walls where the bar spacing
Y/C I assume that the check has also been made on #3’s, #4’s,
and #5’s using the revised database. If not, this should be
done before we make the change.
Y/C Given that the “break point” is now the No. 6 bar size, should
we consider going to 1.0 for all bars and eliminate the bar
factor completely? How significant would this be relative to
use of No. 5 bars and smaller?
N
It is impossible to determine if the “new” data available for #6
bars has changed the distribution significantly. I assume that
is the case. However, maybe if we had more data for # 5
bars, we would recommending a change there as well. This
change seems to be tinkering with the code without any
indication that #6 bars are a special problem. Since we do
not have a sliding function, the break has to be made
somewhere and I am not persuaded that the change is
needed.
Responses
(to be provided by individual code proposal
authors)
would reduce the likelihood of a splitting failure.
Anderson
CB001
3
22
Wyllie
CB004
2
3
LUTZ
CB004
2
20
Paulson
CB004
2
21
Y/C See above comment
C
Is this true? A615 is no longer the most widely used?
Y/C Inasmuch as the extension-under-load method has been
removed and the former provisions of 3.5.3.2 have been
removed, it is desirable to educate the typical user by adding
to R.3.5.3.1—
N
The commentary statement is not relevant. Such
a statement should reside, for example, in
Committee 439's report on properties and
availability of steel reinforcement.
Agree. Add a new fifth paragraph to R3.5.3; on
Page 2, Line 21, insert:
“Inasmuch as these ASTM specifications now employ the
offset method to determine yield strength, requiring yield
strength to be taken as the stress at a strain of 0.35 percent
for bars with fy exceeding 60,000 psi is no longer required.”
Inasmuch as these ASTM specifications now employ
the offset method to determine yield strength,
requiring yield strength to be taken as the stress at a
strain of 0.35 percent for bars with fy exceeding
60,000 psi is no longer required Use of the offset
Lines 21-22 and 26-28
See response below to Wyllie.
method provides a procedure to use a constant
limiting plastic strain (0.2 %) to define the yield
strength, which is valid and consistent at any
strength level.
The commentary clause contains a factual error: the
specified absolute minimum tensile strength for ASTM A706
Substitution initiative is withdrawn.
GR60 is 80,000 psi and also 1.25 times actual yield, which is
less than the 90,000 psi required for A615 GR60 for actual
yield strengths up to 72,000 psi. This is not “more restrictive”.
Statistical analysis of a database of mill test data (The
University of Kansas, Structural Engineering and Engineering
Materials, SL Report 04-1, December 2004) finds that some
14% of A706 GR60 bars do not satisfy the 90,000 psi
requirement of A615 GR60. When the substitution is
performed, what is the consequence of having a decreased
specified tensile strength in some instances? This needs to
be brought out and discussed in the ballot statement, even if
all that happens is that we state that there is no
consequence.
Furthermore, while I have no major objection to the basic
concept of substitution under 3.5.3.2, the background
statement does not explain why we are making this particular
change. Is there a demand from designers for this? An
explanation is needed.
Wyllie
CB004
2
21
N
Why do we need this in the Code? Should be a routine
project RFI.
Agree. On Page 2, delete lines 21-22 and 26-28.
And on Page 1, Line 42, delete "3.5.3.2 and".
Paulson
CB004
2
22
N
Lines 22-24 and 31-32
See above response to Lutz.
While the bar producers have moved to the 0.2% offset
method, the Code included the 0.35 percent strain
requirement for structural engineering purposes, not bar
production purposes. We need to explain in the background
statement why we no longer have structural engineering
concerns about higher strength bars that do not exhibit
elastic-plastic stress strain curves.
The producers of steel reinforcing bars did not
initiate the revision to adopt the offset method in
the ASTM standards. Rather, the revision was
championed by a seasoned metallurgical
engineer who is employed by a firm that
produces vanadium and is a supplier of vanadium
alloys. A metallurgical engineer with the Illinois
DOT also played a role in the revision process.
The intent of the revision was not for bar
production purposes.
Fiorato
CB004
2
26
N
I am not sure I understand the proposed changes to Sections Agree to deletions as noted in above response to
3.5.3.2 and R3.5.3.2 relative to use of A706 steel.
Wyllie.
Why does 3.5.3.2 need to be changed to state that A706
Grade 60 can be substituted for A615 Grade 60? Isn’t it
already permitted in Section 3.5.3.2 of ACI 318-08 which
states that “Deformed reinforcing bars shall conform to one of
the ASTM specifications listed in 3.5.3.1, except that for bars
with fy exceeding 60,000 psi, the yield strength shall be taken
as the stress corresponding to a strain of 0.35 percent. See
9.4” The Code does not restrict use of A706 Grade 60 vs.
A615 Grade 60. It only gives a method for determining the
yield strength when fy exceeds 60,000psi.
Given the changes to the ASTM standards as noted in the
rationale for CB004, can 3.5.3.2 be deleted? (This would also
require deleting the proposed “3.5.3.2 and” on p. 1 Line 42 of
CB004 and renumbering the remainder of the sections.)
Even if the Subcommittee chooses to keep the reference to
substituting A706, is the proposed wording in R3.5.3.2
needed? What is meant by indicating “the requirements for
mechanical properties and chemical composition” are more
“restrictive”? If the mechanical and chemical requirements
need to be more restrictive we should mandate use of A706
only. Don’t we mean that either the requirements for ASTM
A706 Grade 60 or the requirements for ASTM 615 Grade 60
are satisfactory unless specifically noted? Presumably we
would not permit the substitution if they were not at least
equivalent for purposes of design by the Code. Therefore,
suggest deletion of the entire commentary in section R3.5.3.2
whether or not the statement on substitution of A706 is
retained.
Wyllie
CB004
French
CB008
Anderson
CB008
Meinheit
CB008
N
No test data or other reported failures were given as
evidence to justify this change. If evidence exists, they the
change may be justified.
Jirsa
CB008
N
Has a problem with these cases been identified?
Fiorato
CB008
N
The rationale for this change in effect states that the
lightweight factor must be applied to deformed bars in
compression for “consistency” in the Code. What do test data
say about whether the factor is needed for compression lap
splices in lightweight concrete and, if needed, what value
should be used? Have there been field problems with the
current provisions?
2
34
N
I believe we need a Commentary sentence or two why this
prehistoric 0.35 strain requirement has been removed.
N
I think that it is good information to have out on the table for
discussion by ACI318B, and prior to making further changes
for consistency regarding the use of the lightweight factor for
concrete, the committee should revisit the appropriateness of
the lightweight factor for the compressive development length
and seek input from ACI 408.
Y/C Is there any research to back up this change? Or is this just
a bookkeeping / editorial change to stay consistent in the
Code?
1
19
Assuming the data indicate the factor for compression is
needed, the wording of 12.16.1 could be clearer. Suggest
something like:
12.16.1 — Minimum compression lap splice length shall be
the largest of (a) through (d):
Agree. See above response to Lutz.
(a) (0.02fy /λ f’)d , with λ as given in 12.2.4(d)
(b) 0.0005fydb, for fy ≤ 60,000 psi
(c) (0.0009fy -24)db for fy > 60,000 psi
(d) 12 in.
For f'c less than 3000 psi, the length of lap shall be
increased by one-third.
Wyllie
CB008
2
4
Paulson
CB008
3
8
LUTZ
CB008
3
8
N
No objection to the proposed change, but by the same logic
we should apply the same lambda reduction for development
of prestressing strand in 12.9.
Y/C Shouldn’t there be a set of parenthesis around “lambda-rootfc-prime” to prevent a possible misinterpretation? Someone
could divide by lambda and then multiply by root-fc-prime.
Same thing would apply to this same expression as found in
12.3.2.
N
Lines 8-9
Remove the change. Insertion of the compression
development length is inconsistent with the splice lengths
given which are significantly larger. To be cautious one could
introduce the λ into the current splice expressions. If this
were done then λ should also be added to the 0.0003d bfy
expression in 12.3.
LUTZ
CB008
3
8
Tolles
CB008
3
8
Y/C Also note that there is an extra ‘the’ in the 3rd to last line of
R12.16.1.
N Lines 8-9
I ran some numbers with fc 2500 – 8000 psi and rebar fy 60
or 75 ksi and it doesn’t appear that the added equation
based on compression development length to include λ
would ever govern over the existing equations.
Include λ in existing equations:
12.16 — Splices of deformed bars in
compression
12.16.1 — Compression lap splice length shall be
0.0005fydb/ λ, for fy of 60,000 psi or less, or (0.0009fy
-24)db/ λ for fy greater than 60,000 psi, but not less
than 12 in and with λ as given in 12.2.4(d). For f'c
less than 3000 psi, length of lap shall be increased
by one-third.
French
CB013
N
Lobo
CB013
A
Paulson
CB013
Y
Mize
Browning
CB013
Y
CB013
Y
Tolles
CB013
Jirsa
CB013
Y
Cook
CAGLEY
CB013
Y
CB013
Y
Darwin
CB013
N
The key goal of the proposed change is to allow the net
bearing area of the head Abrg to be based on the gross area
of the head minus that area of the bar unless an obstruction
exceeds the limits in newly proposed section 3.5.9(d). The
proposed changes in 3.5.9 include specific restrictions that
are not in 318-08, but the meaning of proposed 3.5.9(c) is
not clear in light of the restriction that is retained in 3.5.9(d).
The proposal does not include a technical justification for
changing the definition of Abrg. Such a justification is needed
before approving this proposal. Under any circumstances, a
less complex modification would be advantageous.
Fiorato
CB013
N
I have questions regarding the rationale for the proposed
changes and the means to implement the changes.
It is my understanding that this requirement would exclude
one of the systems upon which the code provisions for
headed bars is based. We should further consider the
implications of this change.
Y/C Hopefully these detailed requirements for head design can be
transferred to ASTM A970 in the future and removed from
318
1
0
The assumption that the shapes shown between Lines 10
and 11 on p. 2 of CB013 may not provide the same
anchorage as the shapes used in the tests that served as the
basis for the provisions in ACI 318-08 (between Lines 14 and
15 on p.1) seems logical. However, from the figures it is not
clear that the “non-conforming” products would in fact meet
the requirements of ACI 318-08 Section 3.5.9. Are they being
used in practice and do they meet the current requirements
of 3.5.9?
Assuming data do support the rationale and the changes are
needed, should some of the proposed revisions to 3.5.9
really reside in ASTM A970? The ASTM A970 standard is
supposed to cover headed steel bars for concrete
reinforcement, including deformed bars.
Currently Section 4.1.6 of ASTM A970-07 states the
purchaser must specify: “Head geometry, including thickness,
height, width, and cross-sectional area.” However, the
standard can (and should) be updated to include the
geometric limitations related to obstructions. Actually, ASTM
A970 should also include the requirement that the net
bearing area of the head Abrg shall not be less than 4Ab. This
is because there is a clause in Section 5.3 of ASTM A970
that permits alternate head designs by the manufacturer if
agreed to in advance by the purchaser. Thus, the
manufacturer is permitted to propose an alternative design
that does not meet ACI 318 requirement on head bearing
area (if the purchaser agrees). The purchaser is usually the
contractor or subcontractor, not the designer. If the contractor
or subcontractor is not aware of the provision in ACI 318, this
could result in “non-conforming” products inadvertently being
used.
I realize this may be considered to be an ASTM committee
issue, but if ASTM A970 is not referenced in ACI 318 it is less
likely it will be used. Therefore, I would expect ASTM
Subcommittee A01.05 to be receptive to recommendations
from ACI 318 Subcommittee B.
Darwin
CB013
1
5
N
To be accurate, line five should read “…are based in part on
testing reported in the following references…”
Darwin
CB013
2
6
N
Lines 6-10
This is not an accurate statement, in that “nonconforming”
heads of the type shown were available at the time of the
tests reported in the cited references. It’s not clear that this
statement is needed. It would be satisfactory to indicate that
they exist and that the provisions of 12.6.1 and 12.6.2 where
written to preclude their use.
Darwin
CB013
2
12
N
Lines 12-14
This statement is not totally accurate. It’s not participation of
the bar adjacent to the bearing face that is the key concern;
what is of concern is the potential of an obstruction to lower
the anchorage capacity of the head by lowering the load at
which a splitting failure will occur in the concrete.
Darwin
CB013
2
22
N
Lines 22-23
The statement that ”the definition of obstructions given in
3.5.9 appears to be too restrictive” is off base because the
proposed definition of an obstruction in newly proposed
section 3.5.9(d) includes, without change, the language that
has been removed from the current 3.5.9.
Darwin
CB013
3
1
N
Lines 1-2
It is not clear that the proposed changes fully reflect the
heads used to establish 12.6.1 and 12.6.2. If obstructions
such as addressed in proposed 3.5.9(d) were used, they
were used in very few tests.
Gustafson
CB013
3
Darwin
CB013
3
36
36
N
According to ASTM A970/A970M, the headed bar, shown in
Illustration i and Photograph i on Page 1, would be classified
as Class A. Such headed bars were used in the tests upon
which the existing Code provisions are based. What then is
the logic for excluding such Class A headed bars from the
Code? This negative vote will be withdrawn if the exception
on Page 3, Line 36, i.e., "Class B", is deleted.
N
Lines 36-38
I think that we’ll have a problem specifying only Class B
heads because a majority of the tests on which the current
provisions are based were made on (would now qualify as)
Class A heads. In addition, the requirement that heads
“satisfy all of the following additional requirements” is
confusing because the paragraph after section (d) indicates
that section (d) is not mandatory.
Kopczynski
CB013
3
40
Y/C Lines 40-45
(a) and (c) deal with the bearing face; (b) deals with
obstructions on the bar. Reverse (b) and (c) to make the flow
of information more logical.
Ghali
CB013
3
40
N
Lines 40-41
Ghali (recommends N)
3.5.9 Permits only headed bars that satisfy:
“(a) The bearing face shall consist of a surface,
nominally flat surface that lies in a plane perpendicular
to the longitudinal axis of the bar.”
The wording should be changed to clearly permit tapered
heads with the configuration in Fig. R3.5.5 of ACI 318-08.
This type of head should be permitted because:
1. It has been used extensively in testsa,b,c,d and in
practice. It does not need to be approved by a
building official (as required in 12.6.4).
2. Forged heads are permitted; they commonly have
the configuration in Fig. R3.5.5. To enable the
forming of a head, of the required size, by the
forging of a straight bar, it is necessary that the
forging displaces a minimum volume of material.
Thus, the thickness of the head is designed to
provide the required strength with minimum
variable thickness (tapered as in Fig. R3.5.5).
Without minimizing the volume of the material of
the head, an excessive length of the bar has to be
deformed to the shape of the head; this long
length is vulnerable to buckling under the forging
force, rather than forging to the desired
configuration.
3. At the intersection of a straight bar with a plane
bearing face, there is a re-internet corner at which
the bearing stress on the concrete is extremely
high (theoretically infinite). This high stress
concentration is avoided by the fillets connecting
the stem to the head in Fig. R3.5.5.
4. Entrapment of air bubbles below the head during
casting is less likely to occur with the configuration
in Fig. R3.5.5, compared to a head satisfying
3.5.9(a) of CB013. The entrapment of air weakens
the concrete in a critical location.
References:
a. Eligehausen, R., “Report on Pull Tests on Deha
Anchor Bolts,” Report No. DE003/01-96/32, Institut
fur Werkstoffe in Bauwesen, Unversity of Stuttgart,
1996. (Research carried on behalf of Deha
Ankewysteme GMBH & Co. KG (Gross-Gerau)).
b. Gayed, R.B., and Ghali, A., 2004, “Double-Head
Studs as Shear Reinforcement in Concrete I
Beams,” ACI Structural Journal, V. 101, No. 4, JulyAug., pp. 549-557.
c. ACI 421.1R-08, Guide to Shear Reinforcement for
Slabs,” American Concrete Institute, 23 pp. See list
of references in this publication for several
researches using headed bars with tapered head.
d. Birkle, G., Ghali, A. and Schäfer, K., “DoubleHeaded Studs Improve Corbel Reinforcement,”
Concrete International, Vol. 24, No. 9, Sept. 2002,
pp. 77-84. Tests in this research were designed to
fail in compression; however, the tensile stresses in
the headed bars varied between 330 and 480 MPa.
Wyllie
CB013
3
40
N
This is way too complex to bury in Chapter 3, where
designers may not see it. Can’t we just require a bigger head
so the net bearing area on the head minus all obstructions
equals 4 Ab or greater?
LUTZ
CB013
3
44
N
Lines 44-45
It is necessary to illustrate what this provision (c) means. I
don’t know if I understand it or not.
Darwin
CB013
3
44
N
Lines 44-45
The wording in section (c) is not clear, and it appears to
conflict with section (b). It would advantageous, once the
meaning is explained, to combine (b) and (c).
Meinheit
CB013
4
18
Anderson
CB013
5
18
Y/C Add the limits of the distance of the obstruction of
deformations, the head diameter, and diameter of obstruction
to the top figure in Fig. R3.5.9.
N
Add the following terms to clarify the commentary provisions:
≤ 0.5 db
≤ 0.5 (db+ dh)
dh
French
CB016
Jirsa
CB016
1
0
Fiorato
CB016
1
9
Y/C The proposal seems reasonable. Is there any available data
on these systems that can be referenced?
See response to Fiorato.
Y/C Is there any basis for considering all of the coatings to be
See response to Fiorato.
equivalent to epoxy? It may be conservative but if that is the
intent, the commentary should indicate whether any test data
is available to justify this change.
N The rationale states “Because, the outer coating is epoxy, the Yes, there are supporting data. ASTM A775/A775M
bond strength of the dual-coated bars would be similar to that and A934/A934M, and now A1055/A1055M, contain
an annex, which prescribes the qualification
of epoxy-coated bars (ASTM A775/A775M and
requirements for the coated bars. The annexes
A934/A934M).” While this seems to be a reasonable
include a qualification test for relative bond strength.
assumption, are there test data to support the statement?
The relative bond strength is determined in
accordance with ASTM A944, "Standard Test Method
Similarly, for the changes proposed in Section 12.2.4(b) and
R12.2.4, are there supporting data?
Proposed Code change CB016 (and CB013) brings up an
interesting issue for ACI 318 Sub B. Do we need to change
the Code for every new product that comes on the market?
And what are the criteria for making a change? Are we
picking the winners and losers?
for Comparing Bond Strength of Steel Reinforcing
Bars to Concrete Using Beam-End Specimens".
In 2006, bond strength tests of dual-coated bars were
conducted at the University of Kansas. At that time,
ASTM A1055/A1055M did not exist. Hence, the tests
were conducted in accordance with the annex in
A775/A775M.
The results of the tests indicated the dual-coated
bars met the relative bond strength requirement of
A775/A775M.
Discuss at meeting.
Meinheit
CB016
1
14
LUTZ
CB016
1
17
Y/C Is it the intent to preclude the use of epoxy coated or zinc and Discuss at meeting.
epoxy coated A1035 reinforcement? If not then one must
also reference 3.5.3.3 too.
Paulson
CB016
1
30
Y/C The “M” is missing following the second appearance of
A1055.
Anderson
CB100
Y
N
Apparently there are test data available the show that the
dual coating system does not compromise the deformation
height significantly enough to cause a reduction in bond.
Intuitively, I cannot rationalize that the ribs would not be
further reduced in sharpness by the dual coating.
The response to my negative on General Comment #2 is not
compelling, and my negative still remains.
I am not in agreement with the response given to the class
idea for adhesive anchors (Anderson General Comment 2
response). We presently design reinforced concrete with
minimums for concrete strength (4000, 5000, 6000 psi, etc.)
and reinforcing steel (40, 60, 75 ksi, etc.). I think it is a
mistake to design adhesive anchors in a different manner. I
understand the response and the apparent need for the
manufacturers to optimize their product, but I think it is setting
a very bad precedent for the Building Code. Given the
present reasons, I am afraid we will have engineers
specifying unusual minimum concrete strengths in their
designs, such as 4370 psi, or having reinforcing steel
specified to meet a "unconventional" minimum of 67 ksi or
See response to Fiorato.
Agree. Editorial correction is required.
whatever, because that is what the engineer needed. Why
can't we have adhesive classes with minimum strengths, with
a possible Code language caveat saying exact values can be
used if manufacturer’s ACI (or ICC) testing reports are
submitted? (Reference Section 12.6.4, as an example)
While I appreciate the recent comments and rebuttal made
by Silva and Eligehausen on this topic (Sunday 3-8-09,
before the canvassing date), I think their focus is on the
manufacturers and then the designer, not the individuals
charged with the ultimate selection and installation of the
product. I respect their intimate knowledge of this product,
but we need to think more about the end users in the building
process – the engineers down to the installers.
If their argument is considered, in that the system should be
looked at as a bond to reinforcement problem, then should
we move to designing reinforcing bars in a manner similar to
that proposed for adhesive anchors? I think the same
argument could be made. Different reinforcing bars from
different mills would thus have different development and
splice lengths, along with using their actual (not minimum)
yield and tensile strengths. Similar to adhesive anchors,
reinforcing bars are different in that some deformation
patterns may bond better than others; mill scale could
develop faster on one mill’s bar faster than another, bond
could be enhanced to a greater degree by confining
reinforcing; strengths may be greater than minimums in our
present grade system, etc., etc. Isn’t this a dramatic loss of
efficiency, especially when we consider higher strength bars?
Development lengths are selected by the engineer, not the
contractor or reinforcing bar installer, and it does not matter
that much what exact bar (source mill) is supplied by the
contractor. As long as the contractor or sub-contractor
selects the broad class of reinforcement specified in the
contract documents, and provides the proper splice and/ or
development lengths per the placing drawings, it thus meets
the minimum requirements set up as a result of having
different, broad grades (classes) of reinforcement in the
Code. This system seems to work pretty well.
For adhesive anchors, you have a system that is highly
dependent on the product designed by the engineer, selected
by the contractor, and installed by (hopefully) skilled labor.
Under the present proposal to select a system from a myriad
of possibilities, it does matter to a high degree as to what the
exact system is supplied by the contractor - one break down
in this process has the potential for far reaching implications.
Trying to corral this process into classes will hopefully try to
minimize some of these fine-tuned variables. I think we are
trying to provide provisions to design a Swiss watch here, yet
in reality we are building with bulldozers, jackhammers, and
big impact hammers. Providing classes gives the engineer
the latitude to design and specify simple, clear, and broad
classes of systems to cover well over 50 to 75 percent of
the designs. This at least gives the design engineer a place
to start in this highly complex design method.
Having said that, I also believe we should also give the
designer the option to select the exact adhesive anchor
system, designed to the first or second decimal point, and
specified to the nth degree on design documents. I will
further say that the proposed table is a great tool for the
engineer, yet I will submit that if it is given to your average
installer, he will be able to interpret maybe ½ of this
information. Hopefully, our certification efforts will change
this.
Anderson
CB100
N
I believe we need to specify a minimum bond strength of
adhesive to be used in the Appendix D Code design
provisions (say 900 or 1000 psi?).
Kopczynski
CB100
N
The proposed adhesive anchor material is well developed
and clearly supported by good scientific research. In my
opinion, however, much of it does not belong in the building
code.
The code is a basic rule book, not a design manual, which is
where much of the proposed material should reside. To
continue down the path of making Appendix D a design
manual is inconsistent with the 318-14 philosophy of code
simplification. Pages 7 through 15, in particular, contain a
wealth of design information, only a portion of which belongs
in the code.
We cannot stop, nor do we want to stop, the growth of
concrete knowledge. We can, however, separate this
growing knowledge into fundamental rules on the one hand,
and more elaborate design guidance on the other.
Designers, the ultimate users of the code, will thank us for it.
Lobo
CB100
A
Mize
Browning
CB100
Y
CB100
Y
Tolles
CB100
A
CAGLEY
CB100
CB100
Y
Paulson
1
I would like to see this in the code; will support consensus
after discussion in San Antonio. My comments on adding
installation and inspection requirements on plans and specs
have been addressed.
Y/C RE: Proposal for standardization of design and installation
information
Pgs. 1-3
Is this a part of CB100, or is it instead an informational item?
Can’t tell.
Paulson
CB100
1
Y/C RE: Proposal for standardization of design and installation
information
In footnote 1) to the table: delete “correspond to” and replace
with “that are appropriate for use with”.
Fiorato
CB100
1
0
N
I realize I am being repetitive, but the proposed changes for
adhesive anchors add significant complexity and length to
Appendix D. Appendix D should be a stand-alone ACI
standard.
Could ACI 318 include a simplified, but conservative
approach (or alternatively a performance approach – see
CB106) and then refer to the “Anchor Design Standard” if the
Licensed Design Professional wishes to use a more
sophisticated procedure? For many structures, the
sophistication of Appendix D is not warranted.
French
CB100
1
29
Y/C Changed “closes” to “closed”
French
CB100
2
1
Y/C Is the term sNa necessary? In other parts of App. D we do not
indicate that the spacing to develop full breakout strength in
tension is 3hef.
Pg. 3 ln. 22 could change sNa to 2cNa this would be consistent
with the 3hef.
French
CB100
2
12
Y/C In text list expansion anchors and then undercut anchors,
consider showing expansion anchors in figure of post-
installed anchors before undercut anchor
Fiorato
CB100
3
12
N
French
CB100
3
13
Y/C “Adhesive—An adhesive A compound of chemical…”
French
CB100
3
14
Y/C “adhesive may be formulated…”
Meinheit
CB100
3
14
Y/C In line 14 the words “inorganic mortars” imply that there is
cement and water as filler. A mortar to me becomes a mortar
only when hydrated. If there is no water, this is not an
adhesive but a grout. Recommend eliminating inorganic
mortars in the text.
Wyllie
CB100
3
18
French
CB100
3
21
Y/C “…transmit applied loads. Including Cast-in anchors include
headed bolts, hooked bolts (J- or L-bolts), and headed studs.
Post-installed anchors include expansion…”
Gustafson
CB100
3
28
Y/C Suggest replacing "shall be" with something like "are to be" to
avoid the use of mandatory language in the definition.
Fiorato
CB100
3
34
N
N
Suggest moving all definitions to Chapter 2 (or preferably to a
separate standard on Anchoring to Concrete!).
I still believe a 1.5 times anchor diameter hole is too large for
most anchors. I agree it may be appropriate for a very long
embedment but shorter and normal anchors should have a
hole diameter + 1/8 inch for threaded rod and + ¼ inch for
rebar. If you want to keep the 1.5 times in the definition,
there must be a commentary giving good guidance.
Delete the proposed RD.1 commentary on adhesive anchors.
We do not need to define a grouted anchor. Also, the
commentary is nonmandatory. Therefore, the implicit
exclusion of grouted anchors in this location is not
appropriate. Why do grouted anchors need to be mentioned
Nonpersuasive. Current products require range of
hole to anchor diameter up to 1.5 (especially for
bars)
at all?
Anderson
CB100
3
34
N
Replace “Adhesive” with “Grouted.” Although this is a
commentary clarification to the adhesive definition, I believe it
is clearer to define it as the grouted anchor definition.
Wyllie
CB100
3
34
N
Rephrase. This is the definition of a grouted anchor. Say:
“An adhesive anchor has a hole diameter not greater than 1.5
times the anchor diameter. Anchors in larger holes are
commonly referred to as grouted anchors…”
French
CB100
3
35
Fiorato
CB100
4
5
Y/C “Appendix D since because they…”
N
What is the status of the balloting on ACI 355.X (ACI 355.Y)?
The version on the ACI 318 Sub B website is dated August
31, 2008. Ballot Item CB100 states that the ballot on ACI
355.Y closed in October 2008. What has been revised?
Also, what is the precision of the test methods described in
ACI 355.Y for determination of tension load corresponding to
loss of adhesion? That is, if I repeat tests on nominally
identical materials under nominally identical test conditions,
what is the expected variation for the same lab and same
operator; and also for different labs and different operators?
Gustafson
CB100
4
9
Y/C Suggest replacing "capacities" with "strengths".
Gustafson
CB100
4
12
Y/C Suggest replacing "must be" with "is required to be", or revise
the sentence to avoid the use of "must".
French
CB100
4
14
Y/C “of possible conditions (e.g., <list some examples>).”
LUTZ
CB100
4
28
Y/C “states” should be “state”
Jirsa
CB100
4
32
N
Although it appears that the effects of sustained loading have
been reasonably based on available test data, I am not
convinced that adhesive anchors should be used in cases
where sustained tensile load is applied. Options using other
anchor types are available for sustained loading cases. My
concern stems mainly from the lack of quality control during
installation. If the epoxy is not properly handled, the holes
not properly cleaned, the annular space not properly filled,
sustained load is most likely to exploit such quality lapses. It
would seem prudent to allow sustained tension loads of no
more than 10% (or some percentage) of the capacity of the
anchor. Although D.9-Installation of Anchors indicates that
installation must follow manufacturers specifications and
“inspection as required by the legally adopted general
building code,” this is not convincing for cases where
sustained tension will be carried.
I am also concerned that this is work in progress and with
more sustained load tests, the design procedures will
change. Appendix D should be a candidate for a separate
318 document.
Wyllie
CB100
4
32
N
I repeat my previous negative ballot and objection to
including epoxy anchors on sustained tension. I have used
thousands of epoxy anchors/dowels but never used them this
way and death occurred in a Boston tunnel because
someone did. We put something in ACI 318 and it is like a
papel blessing. We are concerned with public safety and
have enough other good products for sustained tension. A
supplemental check is not enough. ACI 318 is used
throughout Latin America. How is an engineer in another
country going to clearly understand this? Delete this
provision and prohibit its use.
Persuasive. Exclude overhead from scope of
Appendix D something like this (note that current
ballot mistakenly omitted revision of RD.2.2):
D.2 — Scope
D.2.2 — This appendix applies to both cast-in
anchors and post-installed anchors. Specialty inserts,
through bolts, multiple anchors connected to a single
steel plate at the embedded end of the anchors,
adhesive and grouted anchors, and direct anchors
such as powder or pneumatic actuated nails or bolts,
are not included. Reinforcement used as part of the
embedment shall be designed in accordance with
other parts of this code. Adhesive anchors installed
overhead to support sustained tension loads are not
within the scope of Appendix D.
RD.2.2 — The wide variety of shapes and
configurations of specialty inserts makes it difficult
to prescribe generalized tests and design equations
for many insert types. Hence, they have been
excluded from the scope of Appendix D. Adhesive
anchors are widely used and can perform adequately.
At this time, however, such anchors are outside the
scope of this appendix. The use of adhesive anchors
installed overhead to support permanent loads is
associated with several factors that may significantly
impact the tension resistance. These include fire
safety, installation quality and creep behavior.
Pending the conclusion of studies into these areas,
the use of adhesive anchors in this condition is
excluded from the scope of this appendix.
Wyllie
CB100
4
32
N
This is not clear. The present D.3.4 is deleted and replaced
with this or what? I believe all this sustained tension of
adhesive anchors should be deleted? Change 0.7 to 0.0.
Cook
CB100
4
34
N
The factor of 0.75 for strength under sustained loading is too
high given the pass-fail data projection method for sustained
loads currently used in ICC-ES AC308 (and now being
balloted by ACI 355 for product approval testing). These
tests are performed at 1100F for 1000 hours at 55% of shortterm strength; the displacement versus time data is then
extrapolated out ten years and measured against a
displacement associated with short-term tests. This test
method does not guarantee that if the test were continued to
1500 hours that creep failure would not occur. Based on a
stress versus time-to-failure test method (that actually
measures the time to creep failure at different load levels),
the current pass/fail test method of 55% load for 1000 hours
would only absolutely guarantee ~35% of the anchor strength
for a 10 year duration at 1100F. The factor of 0.35 would be
conservative and higher values would be permitted based on
a products stress versus time-to-failure evaluation.
The stress versus time-to-failure method actually measures
when creep failure will occur under a given stress level. An
example of a single test is shown below:
The data points of multiple single anchor tests at different
stress levels are then plotted on a stress versus log time-tofailure graph. This data can then be conservatively
extrapolated to predict sustained load failure. The graph
below shows an example product and what could
conservatively be done with anchors that have been tested
using the pass/fail data projection method. The 35%
recommendation is based on 10 years at 1100F (the factor
would be 25% for 50 years at 1100F).
Nonpersuasive. The approach outlined has merit.
However, it has not yet been proven as a viable
method for establishing the creep resistance of
adhesive anchors. Recent testing by the
University of Stuttgart indicates that the current
procedures are, as assumed, conservative
relative to the predicted sustained load strength
developed in this way.
Gustafson
CB100
4
39
Y/C Suggest replacing "analyzed" with "considered". D4.1.3 uses
"considered". D4.1.3 also refers to D4.3 and D4.3 uses
"considered". In CB106, Page 2, Line 40, the word
"determined" is used, i.e., "unless the interaction is
determined in accordance with D4.3"
Wyllie
CB100
4
44
French
CB100
4
50
Wyllie
CB100
4
50
French
CB100
5
7
Y/C “some post-installed expansion anchors may have difficulty
expanding in very high-strength concretes and the bond
strength of adhesive anchors…”
Gustafson
French
CB100
5
8
Y/C Hyphenate "high strength".
CB100
5
29
Y/C “include concrete breakout failure, pullout failure (for cast-in
and post-installed expansion and undercut anchors), sideface blowout failure (for headed anchors), and in the case of
N
Anchors in light-weight concrete should be discussed in
D.3.4, not D.3.5. I would think alone would be sufficient
for undercut and many expansion anchors as the anchors
can expand more easily into the softer lightweight aggregate.
Y/C Consider expanding the explanation in the commentary
calling attention to the important issues associated with
sustained tension and providing caution… importance of
installation and quality control, etc. VERY IMPORTANT.
N
This Commentary is totally inadequate and does not give
adequate warning.
adhesive anchors, bond failure or a combination of bond
failure and concrete breakout.”
Gustafson
CB100
5
30
Y/C Revise the sentence: ". . .The bond model. . ." to avoid the
use "yield" and "capacities"; perhaps something like: "The
bond model in D5.5 may give strengths that are larger. . .'
French
CB100
5
34
Y/C “…calculated and checked separately…”
French
CB100
5
39
Y/C “The anchor shear strength is also dependent on the pryout
strength of D.6.3 for cast-in and post-installed expansion,
undercut, and adhesive anchors.Shear failure modes related
to concrete capacity include concrete breakout failure and
concrete pryout. Additionally…”
Make parallel with earlier part of paragraph line 28.
Also consider referring to D.6.2 and D.6.3 within the sentence
related to shear.
LUTZ
CB100
5
39
Y/C Edit as follows: “…for post-installed adhesive anchors…”
since it implies that there are adhesive anchors that are not
post-installed.
LUTZ
CB100
5
41
Y/C Revise as follows: “…are dependent on limited by the
minimum…” since they provide the lower limit. The strengths
can be dependent on spacings and edge distances larger
than the minimums.
French
CB100
5
42
Y/C “…of anchors…post-installed anchors recognizes….”
LUTZ
Meinheit
CB100
CB100
5
42
Y/C Delete anchors: “…design of anchors for…”.
5
42
Y/C Reads: The design of anchors post-installed anchors… Strike
the first anchors.
Gustafson
CB100
5
42
Y/C In the sentence, "The design of anchors post-installed. . . ",
delete "anchors".
French
CB100
5
44
Y/C “…reflected in varied factors, given in D.4.4, based on the
assessment…”
French
CB100
5
47
Y/C Start section with the last two sentences…
RD.4.2.1—The breakout strength of an unreinforced
connection can be taken as an indication of the load at which
significant cracking will occur. Such cracking can represent a
serviceability problem if not controlled. (See RD.6.2.1.) The
addition of reinforcement in the direction of the load…… The
breakout strength of an unreinforced connection can be taken
as an indication of the load at which significant cracking will
occur. Such cracking can represent a serviceability problem if
not controlled. (See RD.6.2.1.)”
French
CB100
5
49
Y/C “and and D.14…”
Do not delete “and”
Meinheit
CB100
5
50
Y/C Reads: … reinforcement on the behavior of the anchors. Add
the
LUTZ
CB100
6
16
Y/C Lines 16-22
I feel that it is preferable to have the 2 sentences relating to
355.2 first and then the 2 sentences relating to 355.X rather
than alternating back and forth.
French
CB100
6
17
Y/C Keep info on 355.2 together and the info on 355.X together
and make wording parallel:
“The ACI 355.2 tests for sensitivity to installation…device.
Corresponding tests in ACI 355.X determine the category for
a particular adhesive system. In the ACI 355.2 tests…are
considered. In the ACI 355.X tests for adhesive
anchors,sensitivity to installation procedures determine the
category for a particular adhesive system considering the
influence of adhesive mixing…”
French
CB100
6
37
Y/C This is just a fix not related to adhesive anchors, should it be
handled separately?
LUTZ
CB100
7
5
Y/C Mentioning ‘multiple failure surfaces” without a better
description of their location or nature is not very helpful to an
engineer who is trying to understand behavior.
LUTZ
CB100
7
6
Y/C Remove ‘whereby’ and make the last portion a separate
sentence.
LUTZ
CB100
7
11
Y/C Does adding this phrase ‘over the service life of the anchor’
muddy the water? Do we have to predict the service life of
anchors we design? Remove it from spec and place in
commentary if at all.
Wyllie
CB100
7
11
N
No cracks over the service life of the anchor! In 50 years no
flexural tension, no shear cracks in floor or wall due to
extreme wind or an earthquake, no random shrinkage crack.
In other words, all concrete is cracked. So delete all
provisions for uncracked concrete.
Nonpersuasive. The current text leaves the
determination of cracked concrete up to the RDP.
Assuming that all concrete is cracked would
impose an additional safety factor across the
board, which is fine, but it would also require the
testing of all anchors in accordance with the
requirements for cracked concrete, which is a
significant change in the current requirements.
Paulson
CB100
7
24
Y/C Change within heading: “and undercut anchor” to read
instead “and post-installed undercut anchors”
Paulson
CB100
7
25
Y/C Near the end of this sentence, change “and” to “or”.
Paulson
CB100
7
27
Y/C Change within heading: “and undercut anchor” to read
instead “and post-installed undercut anchors”
Wyllie
CB100
7
31
Meinheit
CB100
8
14
Darwin
CB100
8
14
N
If we continue to allow adhesive anchors in sustained
tension, all of the values in D.5.5 over the next 3 to 4 pages
need to be separated between anchors in sustained tension
and anchors designed for tension, like the seismic anchorage
of equipment in a slab.
Y/C The designer has to start calculations somewhere. It is
assumed the adhesive anchor still requires the selection of a
category in order to get a factor for design. Because there
are an infinite number of bond stresses to choose from and
then determine how the anchor performs in the qualification
tests plus all the other reductions required now for adhesive
anchors, it seems we should only allow the best performing
adhesive anchors to be used with Appendix D thus reducing
the bond stress values for design to one of two common
values and requiring the best performers so is the largest
value. If simplifications are not made to a common value of
bond stress and conservative 's are not used, the designer
will only use adhesive anchors in dominant shear
applications. There are too many variable decisions that must
be made by the designer when designing in tension. This
procedure is still very complicated and the designer will be
driven back to an ASD approach or not use adhesive
anchors.
N
Lines 14-24
During the Sub-B meeting in St. Louis, the general
consensus seemed to be that adhesive anchor systems
should be classified by class or grade so that the engineer
could design an anchorage system without selecting the
specified system. The principal author of this section
believes that such an approach would not allow a designer
to take full advantage of the best systems that are available.
I believe that this response represents false logic. It’s the
equivalent of saying that we cannot design beams for
flexure because we don’t know the exact yield strength of
Nonpersuasive. Establishment of strength
classes is unworkable and will lead to a "race to
the bottom" that results in products that meet only
the minimum requirements.
the reinforcing steel. In the current case, the goal is not to
specify some safe lower-bound strength (such as suggested
by RD.5.5.2 starting on page 11, line 6) nor is it to include all
contingencies. It is, rather, to establish grades of adhesive
systems. These grades should include installation methods,
hole diameters, etc. If a single system can range in strength
anywhere from 200 to 2300 psi (response to Anderson
negative), then one wonders who can design any system
and can the engineer of record check a design? Once
grades are established, the designer can take advantage of
the best systems by specifying the highest grade of
adhesive system. Anchor design is very complex. Sub-B
has an opportunity to require simplification at this time. We
should take advantage of that opportunity.
Wyllie
CB100
8
16
N
I repeat my previous negative vote that we cannot use these
provisions without test data from ACI 355.X. The response to
my previous negative refers me to the Commentary. Lets
give a value of Tcr of 150 or so in the Code and give guidance
in the Commentary of the expected ranges. So an engineer
can do a design with a value of Tcr he understands from code
and commentary and can then specify an epoxy anchor with
a minimum value of Tcr so the Contractor knows what he
must supply. If all guidance is to be in the Commentary, then
we need to hold the designers hand, show him what to
assume in calculations and what to specify.
Persuasive. Move 150/500 values to the code:
D.5.5.2 — The basic bond strength…
The values for τcr and τuncr shall be based on the 5
percent fractile of results of tests performed and
evaluated according to ACI 355.X. Where values in
accordance with ACI 355.X are unavailable, the
following values shall be permitted to be used:
τcr
= 150 psi
τuncr = 500 psi
RD.5.5.2 — The equation for basic bond strength for
adhesive anchors as given in Eq. (D.x5) represents a
uniform bond stress model which has been shown to
provide the best prediction of adhesive anchor bond
strength through numerical studies and comparisons of
different models to an international data base.
Initial design assumptions of τcr = 150 psi and τuncr =
500 psi are sufficiently conservative for most products. In
all cases, adhesive anchors that have not been evaluated in
accordance with ACI 355.X are not permitted for structural
applications.
D.x2
Wyllie
CB100
8
17
N
So I do this analysis of cracking that is proposed and
conclude my anchors in the floor slab may be subject to
shrinkage cracks and diaphragm shear cracks, how do I
control them with flexural reinforcement or confining
