1. Anchor
Channel Systems
2. HAC
Portfolio
3. HAC
Applications
4. Design
Introduction
5. Base material
6. Loading
ϕ factor for concrete breakout strength in tension
Condition A (ϕ=0.75) is considered when
Cracked
• No Supplementary reinforcement is present
Uncracked
10. Design
Software
11. Best
Practices
12. Instructions
for Use
13. Field Fixes
14. Design
Example
Anchor reinforcement in tension
As opposed to supplementary reinforcement, anchor
reinforcement acts to transfer the full design load from the
anchors into the reinforcement. Hence, concrete breakout
is precluded. Where anchor reinforcement is developed in
accordance with ACI 318 on both sides of the breakout surface
for an anchor of an anchor channel, the design strength of the
anchor reinforcement shall be permitted to be used instead
of the concrete breakout strength in determining ΦNn or ΦVn,
dependent upon the if the load is tension or shear. A strength
reduction factor of 0.75 shall be used in the design of the anchor
reinforcement. Anchor reinforcement can be utilized in tension,
longitudinal shear, and perpendicular shear. An explicit design
and full development are required for anchor reinforcement.
Condition B (ϕ =0.70) is considered when
9. Special Anchor
Channel Design
ψ cp,N = modification factor for splitting
ϕ
A
B 0.75
0.70
In accordance with the provisions of AC232 D5.2.10.9, the
tension anchor reinforcement shall consist of stirrups made
from deformed reinforcing bars with a maximum diameter of 5/8
in (No. 5 bar)
c ac = critical edge distance for splitting
c cr,N = critical anchor edge distance
c s,min = minimum edge distance
ψ cp,N
ed Concrete Uncracked
With Supplementary
Reinforcement
concrete with
Cracked
Concrete reinforcement
supplementary
y cp , N
Figure 7.3.2.17 — Arrangement of anchor reinforcement for anchor channels
loaded in tension, plan view.
1
ì æ c a , min
= MAX í ç ç
î è c ac
ö
÷ ÷
ø
æ c cr , N
; ç ç
è c ac
ö ü
÷ ÷ ý
ø þ
1
1 1
1
= effective embedment depth
= factored tension load
= development length
= development length in tension of a deformed bar or
deformed wire with a standard hook, measured from
critical section to outside end of hook
Figure 7.3.2.17 — Arrangement of anchor reinforcement for anchor channels
loaded in tension, section view.
Where anchor reinforcement is developed in accordance with
ACI 318-11 Chapter 12 or ACI 318-14 Chapter 25 on both sides
of the breakout surface for an anchor of an anchor channel,
the design strength of the anchor reinforcement, ϕN ca , shall be
permitted to be used instead of the concrete breakout strength,
ϕN cb , in determining ϕN n . The anchor reinforcement for one
anchor shall be designed for the tension force, N aua , on this
anchor using a strut-and-tie model. The provisions in Figure -
7.3.2.17 shall be taken into account when sizing and detailing
the anchor reinforcement. Anchor reinforcement shall consist of
stirrups made from deformed reinforcing bars with a maximum
diameter of 5/8 in. (No. 5 bar) (16 mm). A strength reduction
factor, ϕ, of 0.75 shall be used in the design of the anchor
reinforcement.
Cast-In Anchor Channel Product Guide, Edition 1 • 02/2019
173
Figure 7.3.2.16 — Arrangement of anchor reinforcement for anchor channels
loaded by tension load at an edge.
h ef
N ua
ℓ d
ℓ dh
The basic concrete breakout strength can be achieved if
the minimum edge distance ca,min equals c cr,n . Test results,
however, indicate that it require minimum edge distances
exceeding c cr,n to achieve the basic concrete breakout strength
when tested in uncracked concrete without supplementary
reinforcement to control splitting. When a tension load is
applied, the resulting tensile stresses at the embedded end
of the anchor are added to the tensile stresses induced due
to anchor installation, and splitting failure may occur before
reaching the concrete breakout strength. To account for this
potential splitting mode of failure, the basic concrete breakout
strength is reduced by a factor ψ cp,N if c a,min is less than the
critical edge distance c ac . If supplementary reinforcement to
control splitting is present or if the anchors are located in a
region where analysis indicates cracking of the concrete at
service loads, then the reduction factor ψ cp,N is taken as 1.0. The
172
Figure 7.3.2.15 — Arrangement of anchor reinforcement for anchor channels
loaded by tension load in a narrow member.
Cracked concrete
1
If c a,min ESR
< c ac 3520
ESR 3520
eq (18)
If CaminCac a,min ESR
3520 eqn (17)
The modification factor for anchor channels designed for
uncracked concrete without supplementary reinforcement to
control splitting, ψ cp,N , shall be computed in accordance with Eq.
(17) or (18). The critical edge distance, c ac , shall be taken from
Table 8-4 of ESR-3520.
Condition
Tension* (AC232 D5.2.10.9)
Figure 7.3.2.14 — Cracked and uncracked concrete.
• Supplementary reinforcement is present
• Reinforcement does not need to be explicitly designed for the
anchor channel
• Arrangement should generally conform to anchor
reinforcement
• Development is not required
8. Reinforcing
Bar Anchorage
presence of supplementary reinforcement to control splitting
does not affect the selection of Condition A or B.
Cracks
7. Anchor Channel
Design Code