________________________________________________________________________
PROBLEM (11.21) An S 310 x 74 steel section (see Table B.9) is used as a column of actual
length L. Based upon a factor of safety ns , determine the critical load Pcr for each of the following
conditions:
(a) Pinned-pinned
(b) Fixed-pinned.
(c) Fixed-free.
Given: L = 4 m, E = 200 GPa, ns = 2
SOLUTION
310 74S
×
:
y
Buckling occurs about y-y axis:
64
6.35 10
yz
I
mI
−
=
×<
26.2
y
rmm
=
(a) 4000 26.2 152.7
e
Lr==
22 9 6
402.8 kN
22
(200 10 )(6.53 10 )
2(4)
cr se
EI
PnL
ππ
−
××
==
=
(b) 0.7 2.8
e
LL==m
29 6
2
(200 10 )(6.53 10 ) 822
2(2.8)
cr
Pk
π
−
××
==
N
m
(c) 2 8
e
LL==
29 6
2
(200 10 )(6.53 10 ) 101
2(8)
cr
Pk
π
−
××
==
N
z
y
z
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