Civil Engineering Reference
In-Depth Information
to the beam (Code 13.6.5), or
91 ft-k, and 15% to the slab, or
16 ft-k. The remaining negative
moment, 157
107
50 ft-k, is allotted to the middle strip.
The portion of the interior positive moment to be resisted by the column strip, as per Table
16.5 of this chapter, by interpolation is (0.68)(
84)
57 ft-k. This 57 ft-k is allotted 85% to the
beam (Code 13.6.5), or
48 ft-k, and 15% to the slab, or
9 ft-k. The remaining positive moment,
84
57
27 ft-k, goes to the middle strip.
4.
Moments for the short-span direction centered on the edge beam:
M
o
(
w
2
)(
n
)
2
8
(0.312)(11.625)(16.75)
2
8
127 ft- k
(a)
Dividing this static design moment into negative and positive portions, as per Section
13.6.3.2 of the Code:
Negative design moment
(0.65)(127)
83 ft- k
Positive design moment
(0.35)(127)
44 ft- k
(b)
Allotting these exterior moments to beam and column strips, as per Section 13.6.4 of
the Code:
2
1
22
18
1.22
1
for edge beam
5.36
1
2
1
(5.36)(1.22)
6.54
5.
The portion of the exterior negative moment going to the column strip, from Table 16.4
of this chapter, by interpolation is (0.68)(
83)
56 ft-k. This
56 ft-k is allotted 85% to the
beam (Code 13.6.5), or
48 ft-k, and 15% to the slab, or
8 ft-k. The remaining negative mo-
ment, 83
56
27 ft-k, is allotted to the middle strip.
The portion of the exterior positive moment to be resisted by the column strip, as per Table
16.5, is (0.68)(
44)
30 ft-k. This 30 ft-k is allotted 85% to the beam, or
26 ft-k, and 15% to
the slab, or
5 ft-k. The remaining positive moment, 44
30
14 ft-k, goes to the middle strip.
A summary of the short-span moments is presented in Table 16.7.
6.
Moments for the long-span direction:
M
o
(
w
2
)(
n
)
2
8
(0.312)(18)(20.75)
2
8
302.3 ft- k
Table 16.7
Short-Span Moments (ft-k)
Column strip moments
Middle strip
Beam
Slab
slab moments
Interior slab-beam strip
Negative
91
16
50
48
9
30
Positive
Exterior slab-beam strip
Negative
48
9
27
26
5
16
Positive
