Civil Engineering Reference
In-Depth Information
EXAMPLE 8.6
Select spacings for #3
stirrups for a T beam with
b
w
10 in. and
d
20 in. for the
V
u
diagram
shown in Figure 8.15, with
f
y
60,000 psi and
c
f
3000 psi.
SOLUTION
(with reference to Figure 8.16)
V
u
at a distance
d
from face of support
72
20
72
44,000
(68,000
44,000)
61,333 lb
V
c
(0.75)(2
3000)(10)(20)
16,432 lb
V
c
2
16,432
2
8216 lb
24,000
8216
24,000
Stirrups are needed for a distance
72
(72)
119.5 in.
c
b
w
d
V
s
a
t left
end
V
u
V
c
/
61,333
16,432
/
0
.75
59,868 which is larger than
4
f
c
b
w
d
(4
3000)
(10)(20)
43,818 lb but less than
8
f
. Therefore the maximum spacing of stirrups
in that range is
d
/4
5 in.
Maximum spacing of stirrups
5 in. when
V
s
d
4
2
4
c
b
w
d
(4
3000)
(10)(20)
43,818 lb. By proportions from the
V
s
column in the table,
V
s
falls to 43,818 lb at approximately
4.66 ft or 56 in. from the left end of the beam.
Maximum spacing permitted to provide minimum
A
v
of stirrups:
4
f
A
v
f
y
0.75
f
(2)(0.11)(60,000)
s
(0.75
3000)(10)
32.13 in.
c
b
w
A
v
f
y
(2)(0.11)(60,000)
(50)(10)
s
50
b
w
26.4 in.
Figure 8.15
