Civil Engineering Reference
In-Depth Information
FIGURE 2.20
Circular column cross section of Example 2.6.
Example 2.6: Design
Design for spiral reinforcement in the following circular column using ACI 318-11:
f
=
4,000 psi
c
f
=
60,000 psi
y
f
=
50,000 psi
yt
Solution:
91
×
ρ=
=
0.0286
>
0.01
O.K.
π
4
2
×
20
Use#3spirals
π
×
π
×−
2
20
A
A
f
f
4
50
4
g
c
yt
ρ=
0.45
−
1
=
0.45
−× =
1
0.0138
s
(
)
2
20
3
ch
4
4
A
dS
×
−×
40.11
sp
ρ=
S
=
=
1.87 in.1in.
>
s
(
)
20
3 .0138
c
<
3in.
Use#3spiral@1
3
4
in.
Confinement models for increasing core strength (justifying ACI 318-11 equation):
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