1. Anchor
Channel Systems
2. HAC
Portfolio
3. HAC
Applications
5. Base material
6. Loading
maximum width of the slot between the channel lips. Insert
the channel bolt in the channel profile and apply the load with
a coupling nut to avoid thread failure. Alternatively, in case of
standard channel bolts, channel bolts may be tested in a steel
template (Figure 7.3.1.6 b). This template shall represent the
inner profile of the channels.
7. Anchor Channel
Design Code
8. Reinforcing
Bar Anchorage
9. Special Anchor
Channel Design
10. Design
Software
In tension Test No. 4 the distance between the support reaction
and any loaded anchor may be smaller than 2h ef to avoid
concrete failure.
1
Where the center-to-center spacing between channel bolts shall
not be less than 3-times the bolt diameter d s .
13. Field Fixes
14. Design
Example
The value calculated from Eq. (17.4.3.4) corresponds to the load
at which crushing of the concrete occurs due to bearing of the
anchor head (CEB 1997; ACI 349). It is not the load required to
pull the anchor completely out of the concrete, so the equation
contains no term relating to embedment depth. Local crushing
of the concrete greatly reduces the stiffness of the connection,
and generally will be the beginning of a pullout failure.
In lightweight concrete subjected to tensile stress, the
aggregate fractures and the surface of the crack is, compared
to the fracture process in concrete containing normal weight
aggregate, relatively smooth. Therefore, the descending (strain
softening) part of the load-deformation curve for normal weight
concrete is less steep than in the case of lightweight concrete.
Hence the strength is reduced using reduction factor λ.
Figure 7.3.1.6 — Test on channel bolts, test series No. 3.
Channel Flexural Strength, фM s,flex
where A use,N is the effective cross-sectional area in tension, in 2
(mm 2 ); and f utb shall be taken as the smaller of 1.9f yb and 125,000
psi (860 MPa)
166
In Test No. 4, concrete failure shall be avoided. This may be
achieved by testing anchor channels with anchors that have an
increased embedment depth.
Per ESR-3520 Section 4.1.3.2.4,
nominal pullout strength (N pn ) is
calculated using ACI 318 anchoring
to concrete provisions. ACI 318-11
Appendix D and ACI 318-14 Chapter 17
provisions.
ϕN pn ≥ N aua
N pn = Ψ c,P . λ . N p
reference ACI 318-14 Eq. (17.4.3.1)
N p = 8 A brg f’ c
reference ACI 318-14 Eq. (17.4.3.4)
f’ c = concrete compressive strength
A brg for anchor channel is found in ESR-3520 Table 8-1
λ
= modification factor for lightweight concrete
λ
= 1 for Normal weight concrete
λ
= 0.85 for Sand Light weight concrete
λ
= 0.75 for All Light weight concrete
Figure 7.3.2.2 — Concrete cone in cracked (left) and uncracked (right)
concrete.
A cracked tension zone is assumed because concrete
possesses relatively low tensile strength, which may be fully
or partly used by internal or restraint tensile stresses not taken
into account in the design. The load-bearing behavior of an
anchor can be significantly influenced by the presence of a
crack passing through the anchor location. For anchor channels
located in a region of a concrete member where analysis
indicates no cracking at service load levels, the following
modification factor shall be permitted
ψ c,p = 1.25
Where analysis indicates cracking at service load levels ψ c,p
shall be taken as 1.0.
Concrete ψ c,p
Cracked
Uncracked 1.00
1.25
Cast-In Anchor Channel Product Guide, Edition 1 • 02/2019
167
Test No. 3 is performed to evaluate the strength of the head of
the channel bolt. All channel bolt sizes have been tested. For
test No. 3, test the channel bolts in a section of channel that is
sufficiently restrained to cause failure of the channel bolt (Figure
7.3.1.6 a). If the channel bolt is intended to be used for different
channel sizes, conduct the tests in the channel profile with the
Pull-out and pull-through failure is
characterized by the anchor being
pulled out, whereby the concrete in the
immediate vicinity of the anchor may
not be damaged.
he nominal strength of the channel
T
bolt, N ss , shall not exceed the value
determined in accordance with the
following equation:
N ss ≥ A use,N .f utb
The flexural strength of an anchor channel shall be established in
accordance to Test No. 4 of AC232. The purpose of this test is to
measure the bending strength of the channel taking account of
the restraint of the deformation of the outer ends of the channel
by the concrete. The tests shall be performed with all sizes
and materials of anchor channels. Anchor channels with two
anchors with a maximum spacing and the minimum distance
between the end of the channel and the anchor axis as specified
by the manufacturer and with an anchor type that provides the
lowest anchor strength shall be tested. The channel bolt with
the smallest head size and maximum steel strength that, when
tested, still results in steel failure of a part of the anchor channel
other than the channel bolt shall be used. If the largest channel
bolt size still results in bolt failure, the bolt failure load shall be
taken as the load corresponding to bending failure. In case of
locking channel bolts in combination with non-serrated channels,
test has been performed with all channel bolt sizes.
Pull Out Strength фN pn
ϕN ss ≥ N bua
ϕM s,flex ≥ M u,flex
Uncracked
Channel bolt strength N ss , and ϕ are
tabulated in ESR-3520 Table 8-11 for
HAC and HAC-T with Hilti channel bolts
(HBC-B, HBC-C, HBC-T and HBC-C-N).
Cracked
Channel Bolt Strength фN ss
7.3.2 CONCRETE TENSILE STRENGTHS
Figure 7.3.2.1 — Influence of crack path on the stress-deformation behavior
of concrete. concrete.(Picture from Anchorage in Concrete Construction, R.
Eligehausen).
Figure 7.3.1.5 — Anchor channel dimensions.
Bending strength M s,flex ,
M s,flex,seis and ϕ are
tabulated in
ESR-3520 Table 8-3 for
HAC and HAC-T with Hilti
channel bolts (HBC-C,
HBC-T and HBC-C-N).
(Figures a and b taken from AC232, Figure 5.8).
b)
This behavior of anchor channel in concrete is influenced by
a multitude of parameters, including the condition of the base
material (cracked or uncracked), the direction of the action
(tension, shear, combined tension and shear, or shear with
lever arm), concrete strength, embedment depth, distance
to neighboring fasteners and to edges, nature of the action
(transitory, sustained, seismic or shock load) and amount
and configuration of proximate reinforcement. In addition,
environmental factors such as corrosion, extreme temperatures,
and fire can affect anchor performance and must be properly
considered in anchor channel design.
Figure 7.3.1.7 — Flexural test on anchor channels.
Photo of an anchor channel
after test; failure by bending
of channel and distortion of
anchor flanges
a)
12. Instructions
for Use
é æ
ù
s chb, i ö ÷ N b ua, i ú
ç
ê
×
1 + å 1 -
ç
÷ N b ua,1 ú
i = 2 ê
ch ø
2b
è
ë
û
n + 1
2
11. Best
Practices
The nominal strength of the channel lips to take up tension
loads transmitted by a channel bolt, N sl , must be taken from
ESR 3520 Table 8-3. This value is valid only if the center-to-
center distance between the channel bolt under consideration
and adjacent channel bolts, S chb , is at least 2b ch (see fig 7.3.1.5).
If this requirement is not met then the value N sl given in table 8-3
must be reduced by the factor
4. Design
Introduction