Civil Engineering Reference
In-Depth Information
8
'
0
"
7
'
0
"
P.I.
P.I.
moment capacity with 2 bars
moment capacity with 4 bars
moment capacity with 6 bars
55
"
23
"
18
"
16
"
20
"
48
"
48
"
+ half
support
width
48
"
+ half
support
width
"bottom" 2 bars
"middle" 2 bars
18
"
+ 54
" =
6
'
0
"
16
"
+ 54
" =
5
'
10
"
1
2
1
2
18
"
+ 23
"
+ 55
"
+ 24
" =
10
'
0
"
16
"
+ 20
"
+ 48
"
+ 25
" =
9
'
1
"
"top" 2 bars
Figure 14.36
Assume
K
tr
0
(1.3)(1.0)(1.0)(1.0)
2.0
0
1.0
d
60,000
3
40
d
b
53.4 diameters
3000
d
(53.41)(1.0)
53.4
Say 54
OK
2.
Section 12.12.3 of the Code requires one-third of the bars to extend beyond P.I. (1/3
6
2 bars) for a distance equal to the largest of the following values (applies to “top” bars in figure).
(a)
d
of web
24
(b)
12
d
b
(12)(1)
12
(c)
(
16
)(24
12)
for 24
span
18
(
16
)(34
12)
for 34
span
25
2
Use 24
for short span and 25
2
for long span
3.
Section 12.10.3 of the Code requires that the bars shall extend beyond the point where they
are no longer required by moment for a distance equal to the greater of:
(a)
d
24
(b)
12
d
b
(12)(1)
12
