Civil Engineering Reference
In-Depth Information
Solving this expression for the equivalent column stiffness and multiplying through
by
K
c
:
(
K
ct
k
cb
)(
k
t
k
t
)
K
ec
(
k
ct
k
cb
)
(
k
t
k
t
)
An examination of this brief derivation shows that the torsional flexibility of the slab
column joint reduces the joint's ability to transfer moment.
After the value of
K
ec
is obtained, the distribution factors can be computed as follows,
with reference again made to Figure 17.8:
K
b
1
DF for beam 2- 1
K
b
1
K
b
2
K
ec
K
b
2
DF for beam 2- 3
K
b
1
K
b
2
K
ec
K
ec
/2
DF for column above
K
b
1
K
b
2
K
ec
17.5
EXAMPLE PROBLEM
Example 17.2 illustrates the determination of the moments in a flat-plate structure by the
equivalent frame method.
EXAMPLE 17.2
Using the equivalent frame method, determine the design moments for the hatched strip of the flat-
plate structure shown in Figure 17.9 if
c
f
4000 psi,
f
y
60,000 psi, and
w
u
276 psf. Column
lengths
9
6
.
Figure 17.9
