Civil Engineering Reference
In-Depth Information
7.9
Uncoated top bars in normal-weight concrete.
A
s
re-
quired
3.68 in.
2
(
Ans.
59 in., 50 in.)
7.10
Repeat Problem 7.6 if the bars are epoxy coated.
3"
3 @3" = 9"
3"
7.11
Repeat Problem 7.7 if lightweight concrete with
3000 psi is used. (
Ans.
64 in., 40 in.)
c
f
3"
#3 stirrups
@ 8" o.c.
4 #9
f
y
=
60,000 psi
f'
c
= 6,000 psi
7.12
Repeat Problem 7.8 if three uncoated #7 bars are
used and
A
s
required
1.65 in.
2
27"
7.13
Repeat Problem 7.9 if the bars are epoxy coated and
if lightweight concrete is used. (
Ans.
100 in., 85 in.)
7.14
The bundled #9 bars shown are uncoated and are used in normal-weight concrete.
A
s
required
3.62 in.
2
f
y
=
60,000 psi
f'
c
= 4000 psi
32"
#4 stirrups
@ 6" o.c.
#9 bars
4"
3"
9"
3"
Measured to c.g. of outside
longitudinal bar
7.15
Repeat Problem 7.14 if the bars are epoxy coated
and used in lightweight concrete with
7.17
Repeat Problem 7.16 if #10 bars are used. (
Ans.
66.3
in., 61.3 in., 57.4 in., etc.)
c
f
5000 psi.
(
Ans.
57 in., 51 in. etc.)
7.16
Set up a table for required development lengths for
the beam shown using
f
y
60,000 psi, and values of
3000, 3500, 4000, 4500, 5000, 5500, and 6000 psi. As-
sume the bars are uncoated and normal-weight concrete is
used. Use ACI Equation 12-1 and assume
K
tr
0.
c
f
7.18
Repeat Problem 7.16 if #6 bars are used.
40"
#3 stirrups
@ 6" o.c.
#8 bars
3"
7.19
Repeat Problem 7.16 if #7 epoxy-coated bars are
used in lightweight concrete. (
Ans.
61.3 in., 56.8 in., 53.1
in., etc.)
3"
3@4" = 12"
3"
