Civil Engineering Reference
In-Depth Information
2
2
"
11"
16"
2
2
"
2
2
"
2
2
"
11"
16"
Figure 10.18
Notes
(a)
Note that
0.65 as initially assumed since the graphs used show
f
s
f
y
1.0 and thus
t
0.002.
(b)
Code requirements must be checked as in Example 9.1. (See Figure 10.25.)
EXAMPLE 10.5
Using the ACI column interaction graphs, select reinforcing for the short round spiral column
shown in Figure 10.19 if
c
4000 psi,
f
y
60,000 psi,
P
u
500 k, and
M
u
200 ft-k.
f
e
(12)(200)
500
SOLUTION
4.80 in.
P
n
P
u
500
0.70
714.3 k
P
n
714.3
(4)(314)
0.569
K
n
c
A
g
f
P
n
e
(714.3)(4.80)
R
n
c
A
g
h
(4)(314)(20)
0.136
f
15
20
0.75
Ag = 314 in.
2
2
2
"
2
2
"
15"
20"
Figure 10.19
