Civil Engineering Reference
In-Depth Information
In SI units ACI Equation 11-5 is
f
c
120
w
V
u
M
u
b
w
d
7
c
b
w
d
V
c
0.3
f
Equation 11-7 is
0.3
N
u
A
g
c
b
w
d
V
c
0.3
f
1
Example 8.7, which follows, illustrates the computation of the shear strength of an
axially loaded concrete member.
EXAMPLE 8.7
c
For the concrete section shown in Figure 8.21 for which
f
is 3000 psi
(a)
Determine
V
c
if no axial load is present using ACI Equation 11-3.
(b)
Compute
V
c
using ACI Equation 11-4 if the member is subjected to an axial compression
load of 12,000 lb.
(c)
Repeat part (b) using revised ACI Equation 11-5. At the section in question, assume
M
u
30 ft-k and
V
u
40 k. Use
M
m
in place of
M
u
.
(d)
Compute
V
c
if the 12,000-lb load is tensile.
SOLUTION
(a)
V
c
2
3000(14)(23)
35,273 lb
12,000
(2000
)(14)(26)
(b)
V
c
2
1
(
3000)(14)(23)
35,850 lb
3.5
3000(14)(23)
61,728 lb
23
"
26
"
3 #9
3
"
3
"
2@4
"
= 8
"
3
"
14
"
Figure 8.21
