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PROBLEM (*11.87) A W 410 x 85 steel column ( Table B. 8) of L e =5-m effective length
supports an eccentric load of P = 400 kN at a distance e from the center of the section measured
along the web (Fig. P11.87). Employ the interaction formula to determine the maximum allowable
value of e.
Given: ( σall ) b = 140 MPa, E = 210 MPa
*SOLUTION
A = 2.26 in.2
I z = 316 ×106 mm 4
y
417 mm
z
P
A = 10.8 × 103 mm 2
c = 417 2 = 208.5 mm
rz = 171 mm
rmin = 40.6 mm
Le rmin = 123.2
e
W 410x85
Equation (11.25):
(σ all )c =
π 2E
1.92( Le rmin ) 2
Interaction formula:
P A
Mc I
+
≤1;
(σ all )c (σ all )b
=
π 2 (210 × 109 )
1.92(123.2) 2
= 71.12 MPa
( P A)ec rz2
P A
+
≤1
7.12 × 106
140 × 106
400 × 103
1
e(0.2085)
+
[
] ≤1
−3
6
10.8 ×10 (10 ) 71.12 (0.17) 2 (140)
e(0.2085)
≤ 0.127 − 0.0141
(140)(0.171) 2
or
e≤
Thus,
0.0129(140)(0.171) 2
≤ 0.253 m
0.2085
e = 253 mm
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