Civil Engineering Reference
In-Depth Information
TABLE 2.4
Layout of Shear Desi
gn Provision of ACI 318-11.
≤
VV
/2
u
φφ<≤φ
VVV
/2
φφ
VV
c
c
c
u
c
u
The larger of
f
The largest of
−φ
φ
Required area of
stirrups, A
v
none
c
bs
f
50
bs
(
VVs
f
)
c
bs
f
50
bs
0.75
and
, 0.75
f
and
w
yt
w
yt
u
c
w
yt
w
yt
f
f
ytd
The smaller of
and
The smallest of
φ
Required
-
Af
VV
Af
fb
Af
b
Af
fb
Af
b
v t
cw
v t
w
v td
,
v t
cw
and
v t
w
50
0.75
−φ
50
0.75
u
c
Stirrup
spacing,
s
For
(
VV fbd
−φ ≤φ
)
4
cw
,
s
is the
,
u
c
2
and 24 in.
The smaller of
d/2
and 24 in.
smaller of
Maximum
-
For
φ
cw
,
4
fbdV V
<
(
−φ ≤φ
) 8
f bd
cw u
c
s
is the smaller of
d
4
and 12 in.
Source:
Courtesy of Portland Cement Association (2013).
According to ACI 318-11, Section 11.4.7.9, and to avoid premature crushing of con-
crete struts,
V
ʺ
8
f bd
. The ACI 318-11 shear design procedure is summarized in
s
c
w
Table 2.4.
Example 2.3: Design
For the simply supported beam shown in Figure 2.16, you should design for the
stirrup demand along the beam, considering the ultimate load shown in the figure
and knowing that
f
=
4,
ksi f
=
50
ksi
c
yt
Solution:
Assume primary steel is #6
Assume stirrups are #3
3
8
1
2
6
8
d
=−−−×=
22"1.5"
19.75"
12 in.
W
u
= 5.5 k/ft
22 in.
28 ft
1.5"
FIGURE 2.16
Beam profile and cross section for Example 2.3.
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