1. Anchor
Channel Systems
2. HAC
Portfolio
3. HAC
Applications
4. Design
Introduction
5. Base material
6. Loading
7. Anchor Channel
Design Code
8. Reinforcing
Bar Anchorage
9. Special Anchor
Channel Design
10. Design
Software
Concrete breakout strength in tension
Outside corners where two anchor channels are present and are
loaded simultaneously are outside the scope of AC232. Most of
the AC232 provisions can be applied to this type of application.
However, the influence of the adjacent anchor channel should
be consider, as the concrete strength may be negatively
impacted. Verification: j N cb ³ N a ua
13. Field Fixes
14. Design
Example
The main difference in the calculation of the concrete cone capacity is the modification
factor to account for influence of location and loading of neighboring anchors ψ s,N .
N cb = N b × ψ s, N × ψ ed, N × ψ co, N × ψ cp, N × ψ c, N
The modification factor for spacing ψ s,N is adjusted to take the loading of the adjacent
anchors into account.
Given an anchor channel with only two anchors equally loaded ψ s,N varies from 0.5 to 1,
if the relative spacing varies from s i = 0 to s i = s cr,N respectively. In practice, if s i =0 the
capacity of each anchor is the half, both together have the same capacity of 1 anchor.
The equation of ψ s,N limits the maximum capacity of the concrete for each anchor
due to the presence of the other cone. Figure 9.2.10.3 shows ψ s,N for two anchors
symmetrically loaded increasing the spacing from 0 to s i = s cr,N .
In this section an extension for the design AC232 to a group of
channels and to channels close to a corner is presented. The
method is valid for standard anchor channels.
The loads are distributed on each channel independently,
according ESR3520 the steel verifications are not affected by
the neighbored channels, some considerations should be done
for the concrete failure modes.
Figure 9.2.10.3 — ψ s,N for two anchors
symmetrically loaded.
The relative concrete utilization of each anchor is considered with the ratio N aua,j /N aua,1 .
In this way if the load on the second anchor is much higher than that on the first, it
results in a lower ψ s,N,1 for the first anchor. Figure 9.2.10.4 shows the variation of ψ s,N for
two anchors with a spacing of 0.5s cr,N varying the load ratio between the two anchors.
The concrete cone capacity is almost proportional to A c,N / A 0c,N like in the CC Method
(Concrete Capacity design method for anchors).
According to ESR-3520 the minimum distance between the two
anchors is 2” 100mm, hence Profis anchor channel software
follows the rule stated in the Figure 9.2.10.1.a and Figure
9.2.10.1.b. The software has to be activated for corner in order to
design the outside corner with two anchor channels.
12. Instructions
for Use
9.2.10 — H
AC AND HAC-T DESIGN: TOP OR BOTTOM OF SLAB
OUTSIDE CORNER WITH PAIR OF ANCHOR CHANNEL
11. Best
Practices
The same considerations are valid as well also for more than two anchors and a linear
superposition applies.
Figure 9.2.10.1.b.
In Figure 9.2.10.3 standard anchor channel with 2 anchors is represented, where
the red rectangle areas are the “influence areas” or idealized breakout surface of
each anchor. Since the anchor spacing is smaller than the critical one there are
several intersections represented by darker shaded area of cone projection. These
intersections are considered with the ψ s,N .
When two HAC channels are placed close to each other or to a
corner only the concrete verifications needed modifications. The
calculation of the anchor loads and of the steel failure modes
is calculated independently for the two different channels. The
method applies in general to a group of channels with the same
edge distance c a1 in profis anchor channel software.
Figure 9.2.10.4 — Graph s vs ψ s,N .
When the second element is enabled the following condition
must be fulfilled (Figure 9.2.10.1.a, Figure 9.2.10.1.b and Figure
9.2.10.1.c):
(d 1 ) + (d 2 ) ≥ 100mm
If second anchor channel is placed at a distance s a1 bi < s cr,N (Figure 9.2.10.8), further
intersections would be generated between the influence areas of the anchors of
first and of the second channel. In the calculation of the concrete cone failure, these
intersections can be considered with the factor ψ s,N including in sum also for the
anchors of the second channel. In this way, the capacity of each anchors is additionally
reduced due to the presence and utilization of second channel and varies smoothly
with the relative distance.
The same considerations are valid as well also for more than two anchors and a linear
superposition applies.
s i =
n = n ch 1 + n ch 2
( x i - x j ) 2 + ( y i - y j ) 2
Moreover, considering the spacing of each single anchor in two dimensions, it is
possible to consider even more anchor channels, and each possible relative position.
Figure 9.2.10.5 — Influence on ψ s,N ,1 (of the
anchor 1) of the relative load on the anchors.
Figure 9.2.10.1.c.
Figure 9.2.10.1: Geometric condition for the second channel after the
activation of the second element at the corner.
1 . 3 h ef
æ
s cr , N = 2 ç ç 2 . 8 -
180
è
The critical spacing for anchors is 3xh eff based on idealized rectangular concrete cone
area. For anchor channels the following equation is in accordance to AC232:
ö
÷ ÷ h ef ³ 3 h ef
ø
Comparison of c cr,N for anchors and for an anchor channels and comparison of the
idealized breakout area for anchors and for an anchor channel of various embedment
depths shows for effective embedment depth smaller than 7.1” (180 mm) the anchor
channels have a larger c cr,N than anchors. The proposed expression assumes a circular
area of the influence areas of each anchor.
The influence area of the anchor of an anchor channel is larger than those of a single
anchor, hence the following equation of s cr,N,corner is proposed:
Figure 9.2.10.1.a.
240
1 . 3 h ef
æ
s cr , N , corner = 2 ç ç 2 . 8 -
180
è
ö
÷ ÷ h ef ³ 3 . 4 h ef
ø
Figure 9.2.10.6 — Graph ψ s,N vs F 2 /F 1 .
Cast-In Anchor Channel Product Guide, Edition 1 • 02/2019
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