sm11 60

________________________________________________________________________
PROBLEM (*11.60) Determine the allowable axial load P for a W 14 x 145 steel
column (see Table B.8) with built-in ends and a length of 36 ft, braced at midpoint C (Fig.
P11.60).
Given: E = 30 x 106 psi, σy = 40 ksi
*SOLUTION
W14x145:
, ri
4
42.7 .Ain=n=3.98 .
26
3
2 (30 10 )
40 10
c
C
π ×
=×121.7=
151.2 37.99
3.98
e
L
r==
Since y
Lr C<c , use Eq. (11.24):
3
5 3 37.99 1 37.99
( ) 1.78
3 8 121.7 8 121.7
s
n=+ − =
33
40 10 1 37.99
[1 ( ) ] 22.13
1.78 2 121.7
all ksi
σ
×
=− =
So,
22.13(42.7) 945
all
Pk==ips
L
e=0.7L
ft =
18
P
P
18 ft
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