Civil Engineering Reference
In-Depth Information
Table 6-2 Minimum Wall Reinforcement (V
u
≤
φ
V
c
/2)
Vertical
Horizontal
Minimum A
s
a
(in.
2
/ft)
Minimum A
s
b
(in.
2
/ft)
Wall Thickness
h (in.)
Suggested
Reinforcement
Suggested
Reinforcement
6
0.09
#3 @ 15
0.14
#4 @ 16
8
0.12
#3 @ 11
0.19
#4 @ 12
10
0.14
#4 @ 16
0.24
#5 @ 15
#3 @ 15
c
#4 @ 16
c
12
0.17
0.29
a
Minimum
A
s
/ft of wall = 0.0012(12)h = 0.0144h for #5 bars and less (ACI 14.3.2)
b
Minimum
A
s
/ft of wall = 0.0020(12)h = 0.0240h for #5 bars and less (ACI 14.3.3)
c
Two layers of reinforcement are required (ACI 14.3.4)
Table 6-3 Minimum Wall Reinforcement (
φ
V
c
/2 ≤ V
u
≤
φ
V
c
)
Vertical and Horizontal
Minimum A
s
a
(in.
2
/ft)
Suggested
Reinforcement
6 0.18 #4 @ 13
8 0.24 #4 @ 10
10 0.30 #5 @ 12
12 0.36 #4 @ 13
b
a
Minimum
A
s
/ft of wall = 0.0025(12)h = 0.03h (ACI 11.10.9)
b
Two layers of reinforcement are required (ACI 14.3.4)
Wall Thickness
h (in.)
Using the same approach as in Section 3.6 for beams, design for required horizontal shear reinforcement in
walls when V
u
>
φ
V
c
can be simplified by obtaining specific values for the design shear strength
φ
V
s
provided
by the horizontal reinforcement. As noted above, ACI Eq. (11-29) must be used to obtain
φ
V
s
:
A
v
f
y
d
s
2
φ
V
s
=φ
where A
v
is the total area of the horizontal shear reinforcement within a distance s
2
,
= 0.75. f
y
= 60,000 psi,
and d = 0.8˜
w
(ACI 11.10.4). For a wall reinforced with No. 4 bars at 12 in. in a single layer,
φ
φ
V
s
becomes:
φ
V
s
= 0.75
0.20
60
(0.8
12˜
w
)/12 = 7.2˜
w
kips
where ˜
w
is the horizontal length of wall in feet.
Table 6-4 gives values of
φ
V
s
per foot length of wall based on various horizontal bar sizes and spacings.
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