Civil Engineering Reference
In-Depth Information
7.28
Calculations show that 3.70 in.
2
of top or negative steel is required for the beam shown. If four uncoated #9 bars
have been selected and if
c
f
5000 psi and
f
y
60,000 psi, determine the minimum development length needed for the
standard 90
hooks shown. Assume bars have 3 in. side and top cover measured from c.g. of bars and are used in
normal-weight concrete. The bars are not enclosed by ties or stirrups spaced at 3
d
b
or less.
c
7.29
If
f
y
75,000 psi,
3,000 psi,
w
D
1.5 k/ft, and
w
L
5 k/ft, are the development lengths satisfactory? As-
sume that the bars extend 6 in. beyond the
L
of the reactions and that
K
tr
0.
A
s
required
3.14 in.
2
The bars are un-
coated, and the concrete is normal weight. (
Ans.
d
69 in.)
f
Compression Splices
7.30
Determine the compression lap splices needed for a
14 in.
14 in. reinforced concrete column with ties
(whose effective area exceeds 0.0015 hs as described in
Section 12.17.2.4 of the Code) for the cases to follow.
There are eight #8 longitudinal bars equally spaced
around the column.
c
(a)
f
4000 psi and
f
y
60,000 psi
c
(b)
f
2000 psi and
f
y
50,000 psi
