1. Anchor
Channel Systems
2. HAC
Portfolio
3. HAC
Applications
5. Base material
6. Loading
V b : Basic concrete breakout strength in shear of a single anchor
in cracked concrete, Vb, shall be the smaller of (a) and (b):
V b = 7 .( l e d a ) 0 . 2 . d a . l × f c ' × ( c a1 )
1 . 5
Longitudinal Concrete Edge Breakout Strength, ϕV cb,x
11. Best
Practices
12. Instructions
for Use
13. Field Fixes
14. Design
Example
• ACI 318-14 (eqn 17.5.2.1c)
A Vco = 4 . 5 .( c a 1 ) 2 Equation (45)
A vco : Projected area for a single anchor in a deep member
Equation (43-b)
V cb, x = ( A vc / A vco ) × ψ ed, V × ψ c, V × ψ h, V × ψ parallel, V .V b
Equation (44)
V b
A vc
A vco
Case I-b:
Case I: Concrete edge failure governs, Ψparallel=1.0
Case I-a:
Full shear forces acting on the 3rd anchor away from the edge.
The anchor close to the edge is anchor 1.
Calculation of projected area for a single anchor in a deep
member,
A vco :
A vco = (1.5c a1 )(2)(1.5c a1 )
A vco = (4.5)(c a1 ) 2
Calculation of projected area of the failure surface, A vc :
A vc = {min (h, 1.5 c a1 ) [min (c a2,1 , 1.5c a1 ) + (c a2,2 , 1.5c a1 )]}
Calculation of projected area for a single anchor in a deep
member,
A vco :
A vco = (1.5c a1 )(2)(1.5c a1 )
A vco = (4.5)(c a1 ) 2
• V ux /3 is applied to the front anchor.
• Projected area is based on the edge distance of the first
anchor.
• C a1 is measured from the edge of the slab to the center of the
first anchor.
• Projected areas are in accordance with ACI 318-14.
Calculation of projected area of the failure surface, A vc :
A vc = {min (h, 1.5 c a1 )[min (c a2,1 , 1.5c a1 ) + (c a2,2 , 1.5c a1 )]}
Figure 7.4.4.1 — Idealized failure planes and projected area of a cast-in anchor in
accordance with ACI 318-14.
186
• Minimum value of V cb is considered of the two cases for
corner anchors
Cast-In Anchor Channel Product Guide, Edition 1 • 02/2019
187
• For shear force parallel to an edge
ψ parallel,V = 2.0
Figure 7.4.4.3 — Projected area due to an anchor channel loaded in shear acting
parallel to the long channel axis. Shear forces acting on the leading anchor.
• AC232 limits the number of anchors to effectively resist
longitudinal forces to three, if more than three anchors are
present.
• Having the full shear load at the 3rd anchor verifies the
adequacy of the concrete as a system (group of anchors).
• C a1 is measured from the edge to the center of the third
anchor.
• Projected areas are in accordance with ACI 318-14.
Shear forces are distributed amongst the three anchors closer
to the edge. The leading/front anchor is the controlling one.
• According to AC232 the shear load V ua,x shall be equally
distributed to not more than three anchors
• c a1 is based on distance from edge to farthest anchor and all
of the shear is assumed to be carried by that anchor.
• Like the concrete breakout tensile strength, the concrete
breakout shear strength does not increase with the failure
surface, which is proportional to (c a 1) 2 . Instead, the strength
increases proportionally to (c a1 ) 1.5 due to size effect.
• The strength is also influenced by the anchor stiffness and
the anchor diameter (Fuchs et al. 1995; Eligehausen and
Balogh 1995; Eligehausen et al. 1987/1988, 2006b).
• The influence of anchor stiffness and diameter is not apparent
in large-diameter anchors (Lee et al. 2010), resulting in a
limitation on the shear breakout strength provided by Eq.(43).
• The constant, 7, in the shear strength equation was
etermined from test data reported in Fuchs et al. (1995) at the
5 percent fractile adjusted for cracking.
• For shear force perpendicular to an edge
ψ parallel,V = 1.0
Figure 7.4.4.2 — Projected area due to an anchor channel loaded in shear acting
parallel to the long channel axis. Full shear loading acting on the 3rd anchor away
from the edge.
= Basic concrete breakout strength in shear
= Projected area of the failure surface
= Projected area for a single anchor in a deep
member
Ψ ed,V
= Modification factor for edge effect
Ψ c,V
= Modification factor cracked/uncracked concrete
Ψ h,V
= Modification factor for concrete thickness
Ψ parallel,V = Modification factor for shear force V ll parallel to the
edge
λ ……Modification for lightweight concrete
Lightweight concrete = 0.75
Sand-Lightweight concrete = 0.85
ℓ e . .….Minimum (h eff, 8xd a ) according to section 17.5.2.2a of
ACI 318-14. ℓ e is the load-bearing length of the anchor for
shear:
ℓ e = h ef for anchors with a constant stiffness over the full length
of embedded section, such as headed studs. ℓ e ≤ 8d a
d a ….Anchor shaft diameter ( value can be taken from Table 8-1
ESR 3520)
f´ c …..Concrete compressive strength (psi) (8,500 psi, max)
c a1 ….Distance from the edge to axis (in.) (edge to center line of
channel)
The shear strength equations were developed from the CCD
method. They assume a breakout cone angle of approximately
35 degrees (refer to Fig. 7.4.4.1) and consider fracture
mechanics theory. The effects of multiple anchors, spacing of
anchors, edge distance, and thickness of the concrete member
on nominal concrete breakout strength in shear are included by
applying the reduction factor of A Vc /A Vco in Equation (43) .
10. Design
Software
b) F
or a shear force parallel to an edge, V cb,x shall be permitted
to be twice the value of the shear force determined from Eq.
(17.5.2.1a), Section 17.5.2.1 (ACI 318-14) with the shear force
assumed to act perpendicular to the edge.
9. Special Anchor
Channel Design
a) F
or a shear force perpendicular to
the edge, by Eq. (17.5.2.1a), Section
17.5.2.1 (ACI 318-14). The basic
concrete breakout strength in shear
in longitudinal channel axis of a single
round anchor in an anchor channel
in cracked concrete, V b , shall be
computed in 17.5.2.2 (ACI 318-14).
f ' c c a 1
8. Reinforcing
Bar Anchorage
The nominal concrete breakout strength,
V cb,x , in shear acting in the longitudinal
direction of an anchor channel in
cracked concrete shall be computed as
follows:
V b = 9 l
( 1.5 )
Equation (43-a)
7. Anchor Channel
Design Code
7.4.4 CONCRETE STRENGTHS IN
LONGITUDINAL SHEAR
4. Design
Introduction