sm11 43

________________________________________________________________________
PROBLEM (11.43) An ASTM A-47 cast-iron pipe of outer diameter d and wall thickness t
is to serve as a pinned-end column of length L and is to support an eccentric load of P with a
safety factor ns (Fig. P11.43). Calculate the largest allowable eccentricity e.
Given: d = 10 in., t = ¾ in., L = 15 ft, P = 160 kips, ns = 2, E = 24 x 106 psi,
σy = 33 ksi
SOLUTION
, (160) 2(160) 320
s
Pn kips=== 22 (10 8.5 ) 21.79 .
4
Ai
2
n
π
=−=
44
(10 8.5 ) 234.6 .
64 4
I
in
π
=−=
From Example A.4:
22 2 2
11
10 8.5 3.28 .
44
rDd=+=+=
in
We have
320 180
14.68 54.88
21.79 3.28
PL
ksi
Ar
== ==
22
50.4648
(3.28)
ec e e
r==
Substitute these into Eq. (11.20b):
3
6
14.68 10
33 14.68 1 0.4648 sec 27.44 24 10 e
⎡⎤
⎛⎞
×
⎢⎥
=+ ⎜⎟
⎜⎟
×
⎢⎥
⎝⎠
⎣⎦
from which
2.09 .ei=n
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