sm11 19

________________________________________________________________________
PROBLEM (11.19) Two C 6 x 10.5 steel channels (see Table B.9) are bolted back to back
as shown in Fig. P11.19, and used as a pinned-end column 8 ft long. Using E = 30 x 106 psi,
determine the buckling load for the two members.
SOLUTION
6 10.5C
×
:
y
44
15.2 . 0.865 .
zy
I
in I in==
Since
yz
I
I
<
, buckling occurs about Y-Y
axis
2
13.09 .Ai=
d=0.5 in.
n
4
22
1
2( ) 2[0.865 3.09(0.5 )] 3.275 .
Yy
I
IAd in=+ = + =
3.275 0.728 .
23.09
Y
rin==
× 96 131.9
0.728
Y
L
r==
Using Euler formula
226
22
(30 10 )(30.9 2)
( ) (131.9)
cr EA
PLr
ππ
×
×
== 105.2 kips
=
z
A
1
z
Y
A
1
Y
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