1. Anchor
Channel Systems
2. HAC
Portfolio
3. HAC
Applications
Lets consider the anchor b 2 with shear V aau,b2 and tension
N aau,b2 of channel b. To find the modification factor ψ s used in
determining concrete breakout capacity in tension and shear of
b 2 .
y s,N,b2 =
1
1.5
1.5
a
é æ x
ù é æ x
ö
ö N a , a 1 ù
N
, b 1
ú + ê ç 1 - b2,a1 ÷ × ua
ú
1 + ê ç ç 1 - b1,b2 ÷ ÷ × ua
a
s cr,N ø N ua , b 2 ú ê ç è
s cr,N ÷ ø N ua a , b 2 ú
ê è
ë
û ë
û
ψ s,V,2 : Shear modification is factor for spacing of b 2 the case
shown in Figure 9.2.8.2 should be found out using the Equation
9.2.8-b as shown below. The shear concrete breakout capacity
of anchor b 2 gets reduced because of presence of anchor b 1 , a 2
and a 1 . The a 2 has effect on shear concrete breakout capacity of
b2, since the concrete breakout failure shear cone generated by
b 2 coincides with breakout cone generated by anchor a 2 . Please
refer to the equation below for calculating the modification
factor.
Equation 9.2.8-b
y s,V,b2 =
1
é æ
x
1 + ê ç ç 1 - b1,b2
s cr,V
ê è
ë
1.5
1.5
ö V ua a , b 1 ù é æ
x b2,a1 ö V ua a , a 1 ù é æ
x b2,a2
÷ ÷ × a ú + ê ç ç 1 -
÷ ÷ × a ú + ê ç ç 1 -
s cr,V ø V ua , b 2 ú ê è
s cr,V
ø V ua , b 2 û ú ë ê è
û ë
ψ co,N and ψ co,V : modification factor for corner influence when
using the method described above should be considered as 1.
This is because here in this method the influence of adjacent
anchor channel is incorporated in spacing modification factor
ψ s,V,b2 and ψ s,N,b2 . Hence there is no fictitious edge consideration
required here in this method.
On other hand, anchor channel can be analyzed using a
simplified method as described below. Here anchor channel a
and b are analyzed individually limiting the side edge distance
as described below.
If C a2 < C cr,N then y co,N
0.5
æ C ö
= ç a2 ÷
ç C ÷
è cr,N ø
Equation 9.2.8-c
0.5
Equation 9.2.8-d
9. Special Anchor
Channel Design
10. Design
Software
11. Best
Practices
12. Instructions
for Use
13. Field Fixes
14. Design
Example
9.2.9 — H
AC AND HAC-T DESIGN: TOP OR BOTTOM OF SLAB MINIMUM
DISTANCE THAT WILL ASSURE THAT THE CONCRETE CONE
DOES NOT INTERSECT BOTH IN SHEAR AND TENSION
If we have 2 times the maximum of
C crN and C crV distance between the two
anchors closest to the edge of an anchor
channel, we can say that there will not
be any influence of the anchor channel
at the other side of the outside corner as
shown in the figure. Please refer to anchor
channel theory for more information
on this topic. A similar concept can be
applied for inside corners as well.
In this case the real side distance can be
used to analyze each anchor channel. The
example illustrated in Figure 9.2.9.1, C cr,N
critical edge distance in tension controls
the x dimension.
The critical spacing for anchors is given
as 3h ef , as described in the following
Figure 9.2.9.2. For anchor channels the
equation 9.2.9.1 is used for S cr,N . Figure
9.2.9.3 shows the comparison of c cr,N
for anchors and anchor channels. For
effective embedment depth smaller than
180 mm the anchor channels have a larger
c cr,N than anchors.
Figure 9.2.9.1 — TOS and BOS outside corner — Tension and perpendicular shear concrete cones does
not intersect.
1 . 3 h ef ö
æ
÷ h ef ³ 3 h ef Eqn 9.2.9.1
s cr , N = 2 ç ç 2 . 8 -
7 . 1 ÷ ø
è
c cr , N = 0 . 5 s cr , N ³ 1 . 5 h ef
S cr , V = 4c a1 + 2 b ch in .( mm )
c cr, V = 0.5 × s cr, V = 2c a1 + b ch in .( mm )
The proposed expression of s i assumes
a circular area of the influence areas of
each anchor. In Figure 9.2.9.3 the circular
area, for the proposed model for anchor
channels is represented, together with
the squared one used for anchors. For
h ef smaller than 6.10 in. (155 mm) the
influence area of the anchor of an anchor
channel is larger than those of a single
anchor. Therefore, for embedment depths
smaller than 6.10 in. (155 mm) the method
can be applied without any modification.
In order to use this concept also for
embedment depth larger than 6.10 in. (155
mm) the following increase for s cr,N,corner
equation 9.2.9.2 is proposed:
1.3 h ef ö
æ
s cr , N , corner = 2 ç 2.8 -
÷ h ef ³ 3.4 h ef
7.1 ø
è
Eqn 9.2.9.2
Figure 9.2.9.2 —ACI 318-14 -Fig. R17.4.2.1—(a) Calculation of A Nco per ACI318-14
Simplified method: An imaginary edge is assumed in between
the channels. The distance between channels is y as seen in
the Figure 9.2.8.2. The anchor channel is modelled with the
side edge distance of the ratio of the distance y to optimize
the concrete in between the channels and to make sure that
the concrete is not being utilized twice. For example channel b
can be modelled to have a right side edge of ¾ y and channel
a can be modeled separately with left side edge distance of ¼
y. Or imaginary edge is assumed to be at ½ y for both anchor
channel a and b. This approach will lead to conservative results
because concrete breakout capacity is reduced in tension and
shear with modification factor ψ co,N and ψ co,V for corner influence
respectively. Please refer equation 9.2.8-c and 9.2.8-d. This
approach assumes a real edge which in turn leads to higher
utilization by reducing the capacity tremendously.
æ C a 2 ö
If C a 2 £ C Cr , v then Y co , v = ç
÷
è C cr , v ø
238
1.5
ö V ua a , a 2 ù
÷ ÷ × a ú
ø V ua , b 2 ú û
8. Reinforcing
Bar Anchorage
ψ s,N,b2 : Tension modification is factor for spacing of b 2 the case
shown in Figure 9.2.8.2 should be found out using the Equation
9.2.8-a. The tension concrete breakout capacity of anchor b 2
gets reduced because of presence of anchor a 1 and b 1 . The
a 2 has no effect on tension concrete breakout capacity of b 2 ,
since the concrete breakout tension failure cone generated
by a 2 does not coincides with breakout cone generated by
anchor b 2 . Please refer to the equation below for calculating the
modification factor for b 2 .
Equation 9.2.8-a
7. Anchor Channel
Design Code
Example:
6. Loading
Having anchor channel “a” closer to anchor channel “b” has
influence on the concrete breakout capacities. In order to
incorporate the influence, the ψ s,N and ψ s,V the modification
factor influencing location of adjacent anchors should be
modified following the concept in AC232. Anchor channel a and
b are modelled in profis anchor channel software individually
with infinite edges to the sides and then incorporating the
modification factor ψ s,N and ψ s,V using the method described
below later by hand calculation. Please note that there will not
be any imaginary corner influence taken into consideration
when the method described below is used. The influence of the
neighboring anchor channel is incorporated into the design by
incorporating the influence in the spacing modification factor.
5. Base material
Design method for analyzing channels besides each
other with concrete cones in tension and perpendicular
shear intersecting each other: This method is based AC232
principles. The capacity of anchor channel should be reduced
because of the presence of the adjacent anchor channel. The
anchor channels installed next to each other and subjected
to perpendicular shear and tension as seen in Figure 9.2.8.2
requires the reduction in the concrete capacities. The reason
for this is that the breakout failure plane in shear has not been
completely developed as represented by the red shaded area
and breakout failure cone in tension is also not been able to
completely developed as represented by brown circle. These
failure planes intersect as seen in the detail.
4. Design
Introduction
Figure 9.2.9.3 — Comparison of c cr,N for anchors and for an anchor channels (left), Comparison of
the idealized breakout area for anchors and for an anchor channel (right)
Cast-In Anchor Channel Product Guide, Edition 1 • 02/2019
239