1. Anchor
Channel Systems
2. HAC
Portfolio
3. HAC
Applications
4. Design
Introduction
5. Base material
6. Loading
• Load transfer in the longitudinal direction shall not rely on
friction.
a
ua , y ,1
V
a
ua , y ,2
= V
a
ua , y ,4
< V
V u , x
3
= V ua a , y ,5
Figure 7.2.8.2 — Triangular load distribution for different anchor channel
system configurations.
Figure 7.2.8.3 - HAC loaded in the direction of the longitudinal channel axis.
160
Cast-In Anchor Channel Product Guide, Edition 1 • 02/2019
161
Figure 7.2.8.4 — Example for the calculation of anchor forces in case of
anchor channels with 5 anchors loaded in shear longitudinal to the channel
axis for steel and pryout failure.
N ua a ,1 = N ua a ,2 < N ua a ,4 = N ua a ,5
ESR-3520 Equation (2)
The tension loads, N aua,i, on an anchor due to a tension load, N ua ,
acting on the channel shall be computed in accordance with Eq.
(1). An example for the calculation of the tension loads acting on
the anchors is given in Figure 7.2.8.1.
V ua a , x ,3 = V ua a , x ,4 = V ua a , x ,5 =
• Longitudinal shear loads shall be transferred by a positive
load transfer mechanism (e.g. mechanical interlock between
the channel bolt and the channel). In the design model it is
assumed that longitudinal shear loads are solely transferred
by the anchors into the concrete. A positive load transfer
mechanism from the channel bolt via the channel and
anchors into the concrete is required.
The bending moment, M u,flex , on the channel due to tension
loads acting on the channel shall be computed assuming a
simply supported single span beam with a span length equal to
the anchor spacing.
If more than one t-bolt are transferring the tension loads on to
the channel then the linear superposition of the anchor forces
for all loads should be assumed as shown in the figure 7.2.8.2.
If in the design the exact position of the load on the channel
is unknown the most unfavorable loading position should be
assumed for each failure mode (e.g. load acting over an anchor
for the case of failure of an anchor by steel rupture or concrete
break-out and load acting between anchor's in case of bending
failure of the channel).
• The shear loads acting in the direction of the longitudinal
channel axis are transferred from the channel bolt to the
channel and by the anchors into the concrete without
considering friction and/or adhesion between channel and
concrete.
æ
ö æ 2 ö
1
k = ç
÷ = ç ÷
A
'
A
'
A
'
+
+
è 3 ø
3
4 ø
è 2
Longitudinal Shear loads:
• The shear load, V ua,x,i , on an anchor due to a shear load, V ua,x ,
acting on the channel in direction of the longitudinal channel
axis shall be computed as follows: For the verification of the
strength of the anchor channel for failure of the anchor or
failure of the connection between anchor and channel, pryout
failure, and concrete edge failure in case of anchor channels
arranged parallel to the edge without corner effects, the
shear load, V ua,x , shall be equally distributed to all anchors for
anchor channels with not more than three anchors or to three
anchors for anchor channels with more than three anchors
(as illustrated in Figure 7.2.8.4). The shear load, V ua,x , shall
be distributed to those three anchors that result in the most
unfavorable design condition [in the example given in Figure
7.2.8.4 the shear load, V ua,x , shall be distributed to the anchors
3 to 5. For the verification of the strength of the anchor
channel for concrete edge failure in case of anchor channels
arranged perpendicular to the edge and in case of anchor
channels arranged parallel to the edge with corner effects,
the shear load, V ua,x , shall be equally distributed to all anchors
for anchor channels with not more than three anchors or to
the three anchors closest to the edge or corner for anchor
channels with more than three anchors (as illustrated in Figure
7.2.8.5).
I
æ l in - s + 0.25 s ö æ 0.75 s ö æ 1 ö
A ' 4 = ç
÷ = ç
÷ = ç ÷
l in
è
ø è l in ø è 2 ø
1 2 1
N ua a ,2 = N ua . . = N ua
6 3 9
5
2 5
N ua a ,3 = N ua . . = N ua
6 3 9
1 2 1
N ua a ,4 = N ua . . = N ua
2 3 3
14. Design
Example
å A '
æ l in - 0.25 s ö æ 1.25 s ö æ 5 ö
A ' 3 = ç
÷ = ç
÷ = ç ÷
l in
è
ø è l in ø è 6 ø
N ua a ,1 = N ua a ,5 = 0
13. Field Fixes
1
æ l in - s - 0.25 s ö æ 0.25 s ö æ 1 ö
A ' 2 = ç
÷ = ç
÷ = ç ÷
l in
è
ø è l in ø è 6 ø
12. Instructions
for Use
k =
Figure 7.2.8.1 — Example for the calculation of anchor forces in accordance
with the triangular load distribution method for an anchor channel with five
anchors. The influence length is assumed as ℓ in = 1.5s.
Shear loads acting on the channel are mainly transferred by
compression stresses between channel profile and concrete
and to a smaller extent by the anchors. However, the anchors
are stressed by tension forces due to the eccentricity between
the acting shear load and the resultant of the stresses in the
concrete. A model to calculate the concrete edge capacity
of channel anchors under shear loading towards the edge is
described in section 7.4.2. It assumes that shear forces acting
on the channel are transferred by bending of the channel to the
anchors and by the anchors into the concrete. This approach
simplifies the real behavior. It has been chosen to allow for a
simple interaction between tension and shear forces acting on
the channel. For reasons of simplicity it is proposed to calculate
the (fictitious) shear forces on anchors using the same approach
and the same influence length as for tension loads. The shear
load, V aua,y,i , on an anchor due to a shear load V ua,y acting on the
channel perpendicular to its longitudinal axis shall be computed
in accordance with the previous Section of tension replacing N ua
in Eq. (3) by V ua,y .
11. Best
Practices
For an arbitrary position of the load N the forces on the anchors
can be calculated in accordance with equation:
N aua,i = k · A’ i · N ua
ESR-3520 Equation (1)
where:
A’ iaua,i = ordinate at the position of the anchor i assuming a
triangle with the unit height at the position of load
N ua and the base length 2ℓ in with ℓ in determined in
accordance with Eq. (1).
10. Design
Software
Tension Loads:
The influence length depends mainly on the anchor spacing,
the moment of inertia of the channel and on the head size.
Further minor influencing factors are the concrete compression
strength, the type of steel (galvanized or stainless steel) and the
state of concrete (cracked or non-cracked). For sufficiently large
head sizes (head pressure p u < 6.f’ c ) the influence length can be
taken as:
ℓ in = 4.93(I y ) 0.05 ·√s ≥ s , in
ℓ in = 13(I y ) 0.05 ·√s ≥ s , mm
ESR-3520 Equation (3)
s
= anchor spacing, in. (mm)
N ua = factored tension load on channel bolt, lb (N)
I y = the moment of inertia of the channel shall be taken
from Table 2.2.1.1
9. Special Anchor
Channel Design
Perpendicular Shear Loads:
Anchor channels is designed for critical effects of factored loads
as determined by elastic analysis taking into account the elastic
support by anchors and the partial restraint of the channel ends
by concrete compression stresses. An alternative, the triangular
load distribution method in accordance with 17.2.1.2.1 through
17.2.1.2.3 (ACI 318-14) to calculate the tension and shear loads
on anchors is permitted.
The stiffness of an anchor channel is less than that of a stiff
fixture. The distribution of tension loads acting on the channel to
the anchors is calculated using a beam on elastic supports with
partial restraint of the channel ends. The stiffness of the elastic
supports corresponds to the displacement of the anchors which
includes the displacements of the channel lips, anchors and
concrete. The distribution of anchor forces can be approximated
by a triangle load distribution with a peak at the applied load
and an influence length l i .
8. Reinforcing
Bar Anchorage
7.2.8 C
ALCULATION OF LOADS ON ANCHORS
OF THE ANCHOR CHANNEL
7. Anchor Channel
Design Code