Civil Engineering Reference
In-Depth Information
Figure 17.11
8.
Computing distribution factors and balancing moments (see Figure 17.12): The author does
not show moments at tops and bottoms of columns, but this could easily be done by multiplying the
balanced column moments at the joints with the slabs by the carryover factor for the columns,
which is 0.55.
A summary of the moment values for Example 17.2 is given in Figure 17.13. The
positive moments shown in each span are assumed to equal the simple beam centerline
moments plus the average of the end negative moments. This is correct if the end mo-
ments in a particular span are equal and is approximately correct if the end moments are
unequal. For span 1,
(0.276)(18)(22)
2
8
94.8
235.8
2
M
135.3 ft- k
+235.8
+215.2
+ 94.7
- 0.7
+ 0.3
+ 0.8
- 5.4
+ 2.9
- 20.4
+ 56.6
+202.0
- 0.4
+ 2.2
- 2.7
+ 20.4
- 10.2
+202.0
- 0.6
+ 1.1
- 6.7
+ 12.0
-113.1
+202.0
beam
C.O. factors
= 0.503
0.56
0.36
0.36
0.36
0.36
0.56
-202.0
+113.1
- 10.2
+ 5.7
- 2.7
+ 1.5
- 0.4
+ 0.2
- 94.8
-202.0
- 20.4
+ 12.0
- 5.4
+ 1.1
- 0.7
-215.4
-202.0
- 56.6
+ 24.0
- 3.4
+ 2.2
- 0.3
+ 0.3
-235.9
Figure 17.12
