Civil Engineering Reference
In-Depth Information
(
)
(
)
φ
V
n
=φ
V
c
+φ
V
s
=φ
10
f
c
h 0.8
ʹ
w
Table 6-5 gives values of
φ
V
c
=φ
2
f
c
h0.8
ʹ
w
and limiting values of
,
both expressed in kips per foot length of wall.
Table 6-5 Design Values of
φ
V
c
and Maximum Allowable
φ
V
n
Wall
Thickness
h (in.)
I
V
c
(kips/ft length of wall)
Max.
I
V
n
(kips/ft length of wall)
6
5.5
27.3
8
7.3
36.4
10
9.1
45.5
12
10.9
54.6
The required amount of vertical shear reinforcement is given by ACI Eq. (11-30):
ρ
˜
= 0.0025 + 0.5(2.5 - h
w
/˜
w
)(
ρ
t
- 0.0025)
where h
w
= total height of wall
ρ
˜
= A
vn
/s
1
h
ρ
t
= A
vh
/s
2
h
When the wall height-to-length ratio h
w
/˜
w
is less than 0.5, the amount of vertical reinforcement is equal to the
amount of horizontal reinforcement (ACI 11.9.9.4).
6.4.1
Example 1: Design for Shear
To illustrate the simplified methods described above, determine the required shear reinforcement for the wall
shown in Fig. 6-3. The service shear force from the wind loading is 160 kips. Assume total height of wall from
base to top is 20 ft.
Figure 6-3 Plan View of Shearwall
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