sm7 139

PROBLEM (7.139) A rectangular beam of the cross section shown in Fig. P7.139 is made of mild
steel with y
σ
= 250 MPa. For bending about the z axis, calculate:
(a) The yield moment.
(b) The moment causing a 15-mm-thick plastic zone at the top and bottom of the beam.
Given: b = 60 mm, h = 80 mm
SOLUTION
Equation (7.53):
(a) 2
1
6
yy
I
Mb
cy
h
σ
σ ==
26
0.06(0.08) (250 10 ) 16
6kN m
=×=⋅
(b) Equation (7.54):
32
3115
40
(16 10 )[1 ( ) ]
23
=× − 22.875 kN mM⋅
=
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