1. Anchor
Channel Systems
2. HAC
Portfolio
3. HAC
Applications
For condition where reinforcement is anchored as illustrated in
figure 7.4.2.9, the concrete breakout strength in perpendicular
shear can be that of the reinforcement strength.
9. Special Anchor
Channel Design
10. Design
Software
Because the anchor reinforcement is placed below where the
shear is applied, the force in the anchor reinforcement will be
larger than the shear force acting on the anchor channel bolts. If
a shear load (V ua,y ) is acting on the anchor channel, the resultant
factored tension force of the anchor reinforcement N ua,re , shall
be computed by the following equation
14. Design
Example
Figure 7.4.2.9b — Internal forces and detailing requirements for anchor
reinforcement to resist shear loads; section view.
Concrete Pryout Strength of Anchor Channels in Shear
Perpendicular to the Longitudinal Channel Axis фV cp,y
Failure load associated with pry-
out; The load-bearing mechanism
of a single headed stud anchorage
subjected to a shear load is illustrated
schematically in Fig 7.4.2.10. The
applied shear load gives rise to
bearing stresses in the concrete. With
increasing load the surface concrete
is crushed or spalled, shifting the
centroid of resistance V b to a location
deeper in the concrete.
V cp = V cp, y = k cp N cb , lb ( N )
k cp = 2 . 0
ESR-3520 Equation (41)
The nominal pryout strength, V cp,y , in shear of a single anchor
of an anchor channel without anchor reinforcement shall be
computed in accordance with Eq. (41).
where:
k cp = shall be taken from ESR-3520 Table 8-10
N cb = n
ominal concrete breakout strength of the anchor under
consideration, lb (N), determined in accordance with
breakout in tension; however in the determination of the
modification factor ψ s,N , the values N aua,1 and N aua,i in Eq.
(10) shall be replaced by V aua,1 and V aua,i , respectively.
Tests indicates that the pryout shear resistance can be
approximated as one to two times the anchor tensile resistance
with the lower value appropriate for hef less than 2.5 in.
The anchor reinforcement of an anchor channel shall be
designed for the highest anchor load, V aua,y , of all anchors but
at least for the highest individual shear load, V bua,y , acting on
the channel. This anchor reinforcement shall be arranged at all
anchors of an anchor channel.
13. Field Fixes
c a1 = edge distance of anchor channel in direction 1
s = spacing on anchors in direction of longitudinal axis of
channel
s cr,v = critical anchor spacing for shear loading, concrete edge
breakout
d a = diameter of anchor reinforcement
ℓ d = development length
ℓ dh = development length in tension of a deformed bar or
deformed wire with a standard hook, measured from
critical section to outside end of hook
12. Instructions
for Use
Also with increasing load and stud elongation, the baseplate
rotates and loses contact with the concrete on the loaded side.
These two mechanisms act to further increase the eccentricity
between the applied shear load V and the stress resultant V b
in the concrete. The moment resulting from this eccentricity
generates a compressive force C between baseplate and
concrete and a tensile force N in the stud. If the tensile force
in the stud exceeds the tensile capacity associated with the
maximum fracture surface that can be activated by the stud,
a fracture surface originating at the head of the stud and
projecting in conical fashion behind the stud forms Figure
7.4.2.11. This is defined as a pry-out failure.
æ e
ö
N ua, re = V ua , y ç s + 1 ÷ lbf ( N )
è z
ø
e s = distance between reinforcement and shear force
acting on the anchor channel (in)
z = internal lever arm of the concrete member, (in)
= 0.85 (h – h ch – 0.5d a )
≤ (2h ef , 2c a1 )
11. Best
Practices
The nominal pryout strength, V cp,y , in shear of a single anchor of
an anchor channel with anchor reinforcement shall not exceed:
V cp = V cp, y = 0 . 75 . k cp N cb , lb ( N )
Figure 7.4.2.10 — Load-bearing mechanism of headed stud anchorage
subjected to shear loading (schematic).
182
Cast-In Anchor Channel Product Guide, Edition 1 • 02/2019
183
Figure 7.4.2.9a — Detailing requirements for anchor reinforcement to resist shear loads; plan view.
Figure 7.4.2.11 — Typical failure body of a stud anchorage far from an edge
loaded in shear : Cross-section of failure body (schematic).
- Anchor reinforcement is effective if rebar is embedded a minimum of 4da (da = rebar diameter) after idealized failure plane in shear meets the rebar.
- Reinforcing outside the anchor channel is effective if it is located within 0.5Ca1 from the center of the outer anchor.
The ICC-ES Acceptance Criteria AC232 includes amendments
to the ACI 318 anchoring to concrete provisions. These
amendments are given in Section 3.1 Strength Design —
Amendments to ACI 318. Part D.6.3.2 (ACI 318-11) and Section
17.5.3.2 (ACI 318-14) of these amendments require the factor
ψ s,N to be modified when calculating concrete pryout strength in
shear. All of the parameters used to calculate ψ s,N in tension are
used except the parameter (N aua,i / N aua,1 ). The shear loads acting
on the anchor elements are substituted for the tension loads
such that (V aua,i / V aua,1 ) is used instead of (N aua,i / N aua,1 ).
ESR-3520 Equation (42)
k cp = 1.0 for h ef < 2.5 in.; and k cp = 2.0 for h ef ≥ 2.5 in.
In accordance with the provisions of ACI 318-14, 17.5.2.10.8.2,
perpendicular shear anchor reinforcement shall consist of
stirrups made from deformed reinforcing bars with a maximum
diameter of 5/8 in (No. 5 bar) and straight edge reinforcement
with a diameter not smaller than the diameter of the stirrups.
Only one bar at both sides of each anchor shall be assumed
as effective. The distance of this bar from the anchor shall not
exceed 0.5ca1 and the anchorage length in the breakout body
shall not be less than 4 times the bar diameter. The distance
between stirrups shall not exceed the smaller of anchor spacing
or 6 inches.
8. Reinforcing
Bar Anchorage
c a1 = edge distance (in)
V cb,y = n
ominal concrete breakout strength in shear
perpendicular to the channel axis of an anchor
channel
7. Anchor Channel
Design Code
æ 2.85 ö
( V cb , y ) , lbf
V ca , y ,max = ç
0.12 ÷
è ( c a 1 ) ø
6. Loading
The anchor reinforcement of an anchor channel shall be
designed for the maximum perpendicular shear load acting at
the anchor channel anchors and channel bolts. Such anchor
reinforcement shall be arranged at all anchors of an anchor
channel. The maximum strength of the anchor reinforcement
(V ca,y,max ) of a single anchor of an anchor channel shall be
computed in accordance with ACI 318-14,
5. Base material
Anchor reinforcement in perpendicular shear,
ACI 318-14 17.5.2.10.1
4. Design
Introduction