HAC_Technical-Guide

174 175
Cast-In Anchor Channel Product Guide, Edition 1 • 02/2019
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
11. Best
Practices
12. Instructions
for Use
13. Field Fixes
14. Design
Example
7.1 & 7.2 Introduction to
Anchor Channel Design
7.3 Anchor Channel Tension Design 7.4 Anchor Channel Shear Design (y) 7.4 Anchor Channel Shear Design (X)
7.5 Interaction Equations
(Combined Loading)
7.6 Seismic Design
Steel Concrete Steel Concrete Steel Concrete
Concrete side-face blowout strength фN
sb
Tension-loaded headed studs provided
with small edge distances can generate
local blowout failures in the vicinity
of the head. Side blow-out failure will
govern the concrete capacity of studs
having small edge distance (concrete
cover) in combination with large
embedment depth. Local concrete side
blow-out failure is caused by the quasi-
hydrostatic pressure in the region of
the head of the stud which gives rise
to a lateral bursting force. The failure
load will increase in proportion to the edge distance c
a1
. For
anchor channels located perpendicular to the edge and loaded
uniformly, verification is only required for the anchor closest to
the edge.
For anchor channels with deep embedment close to an edge
(h
ef
> 2c
a1
) the nominal side-face blowout strength, N
sb
, of a
single anchor shall be computed in accordance with Eq. (19).
)(,ψψψψψNN
Nbc,Nbh,Nbco,Nbg,Nbs,
0
sbsb
Nlb×××××=
a
uasb
NN ³ f
ESR-3520 Equation (19)
N
b
= basic concrete side-face blowout strength in tension
ψ
s,Nb
= modification factor for effect of distance to
neighboring anchors
ψ
a,Nb
= modification factor for effect of influence of the
bearing area of neighboring anchors
ψ
co,Nb
= modification factor to account for influence of corner
effects
ψ
h,Nb
= modification factor to account for influence of the
member thickness
ψ
c,Nb
= modification factor to account for influence of
uncracked concrete
N
sb
= Basic concrete side-face blowout strength
N
sb
= Basic concrete side-face blowout strength
The basic nominal strength of a single anchor without influence
of neighboring anchors, corner or member thickness effects in
cracked concrete, N
0
sb
, shall be computed in accordance with
Eq. (20).
N
lb
,f.Ac5.10N
,f.Ac128N
'
c
brg
a1
0
sb
'
c
brg
a1
0
sb
×××=
×××=
l
l
ESR-3520 Equation (20)
ψ
s,Nb
= modification factor for effect of distance to
neighboring anchors
The modification factor accounting for the distance to and
loading of neighboring anchors, ψ
s,Nb
, shall be computed in
accordance with Eq. (10), however s
cr,N
shall be replaced by
s
cr,Nb
, which shall be computed in accordance with Eq. (21).
).(,4
1,
mmincs
aNbcr
=
ESR-3520 Equation (21)
ψ
s,Nb
= modification factor to account for influence of
uncracked concrete
The following modification factor to account for influence of
uncracked concrete, ψ
c,Nb
, shall be permitted:
ψ
c,Nb
= 1.25
Figure 7.3.2.18 — Blowout failure of a deep anchor near an edge. (Picture
from Anchorage in Concrete Construction, R. Eligehausen).
ψ
g,Nb
= modification factor for effect of influence of the
bearing area of neighboring anchors
The modification factor to account for influence of the bearing
area of neighboring anchors, Ψ
g,Nb
, shall be computed in
accordance with Eq. (22) or Eq. (23).
0.1
4
).1(,4
0.1,4
1
,
1
,
1
³-+=Y<
=Y³
a
Nbg
a
Nbg
a
c
s
nnthencsIf
thencsIf
ESR-3520 Equation (22)
ESR-3520 Equation (23)
where:
n = number of tensioned anchors in a row parallel to the edge
ψ
co,Nb
= modification factor to account for influence of
corner effects
The modification factor to account for influence of corner
effects, ψ
co,Nb
, shall be computed in accordance with Eq. (24).
1.0
c
c
0.5
Nbcr,
a2
Nbco,
£
÷
÷
ø
ö
ç
ç
è
æ
= y
ESR-3520 Equation (24)
c
a2
= corner distance of the anchor for which the resistance is
computed, in. (mm)
)(.,c2c
a1Nbcr,
mmin=
ESR-3520 Equation (25)
If an anchor is influenced by two corners (c
a2
< 2c
a1
), then
the factor, ψ
co,Nb
, shall be computed for c
a2,1
and c
a2,2
and the
product of the factors shall be inserted in Eq. (19).
ψ
h,Nb
= modification factor to account for influence of the
member thickness
The modification factor to account for influence of the member
thickness, ψ
h,Nb
shall be computed in accordance with Eq. (26)
or Eq. (27).
÷
÷
ø
ö
ç
ç
è
æ
+
£
÷
÷
ø
ö
ç
ç
è
æ
+
=³
=³
a1
a1
a1
ef
Nbh,a1
Nbh,a1
c4
c2
c4
h
c2f If
1.0c2f If
ff
then
then
y
y
ESR-3520 Equation (26)
ESR-3520 Equation (27)
where:
f = distance between the anchor head and the surface of
the concrete member opposite to the anchor channel (as
illustrated in Figure 7.3.2.19), in. (mm)
Figure 7.3.2.19 — Anchor channel at the edge of thin concrete member
ϕ factor for concrete side-face blowout strength
Condition A (ϕ=0.75) is considered when
• Supplementary reinforcement is present
• Reinforcement does not need to be explicitly designed for the
anchor channel
• Arrangement should generally conform to anchor
reinforcement
• Development is not required
Condition B (ϕ =0.70) is considered when
• No Supplementary reinforcement is present
Condition ϕ
A 0.75
B 0.70
Anchor cahnnel with deformed rebar anchors
Where anchors consist of deformed reinforcing bars, verification
for concrete breakout is not required provided that the deformed
reinforcing bars are lap spliced with reinforcing bars in the
member according to the requirements of ACI 318-14 Section
25.5. Refer Section 8.6 of Chapter 8 regarding splice length.