Civil Engineering Reference
In-Depth Information
Steel Area (Using
d
15.5 in.)
Taking moments at face of wall,
Cantilever length
10.00
2
6
12
4.50
M
u
(4.50)(4.80)(2.25)
48.6 ft- k
M
u
(12)(48,600)
(0.9)(12)(16.5)
2
198.3
bd
2
From Appendix Table A.12,
0.00345
0.0136 from Appendix Table A.7.
Section is tension
controlled and
0.9 as assumed.
A
s
(0.00345)(12)(16.5)
0.68 in.
2
Use #7 @ 10
(0.72 in.
2
)
Development Length
From Table 6.1 in Chapter 6
1.0
c
side cover
3.50 in.
k
c
one- half of center- to- center spacing of bars
2
10
5
Letting
K
tr
0
c
K
tr
d
b
3.5
0
1.0
2.5
Use 2.5
f
y
f
c
K
tr
d
b
d
d
b
3
40
c
60,000
(1.0)(1.0)(1.0)(1.0)
2.5
3
40
32.86 diameters
3000
d
b
A
s
,reqd
d
0.68
0.72
A
s
,furn
(32.86)
31.03 diameters
d
(31.03)(0.875)
27.15
Say 28 in.
Available development length
assuming bars are cut off 3
from edge of footing
10
0
2
6
3
from face of
wall at section of
maximum moment
4
3
28
OK
(The bars should be extended to a point not less than 3 in. or more than 6 in. from the edge of the
footing.)
Longitudinal Temperature and Shrinkage Steel
A
s
(0.0018)(12)(20)
0.432 in.
2
Use #5 at 8
12.6
DESIGN OF SQUARE ISOLATED FOOTINGS
Single-column footings usually provide the most economical column foundations. Such
footings are generally square in plan, but they can just as well be rectangular or even circu-
