sm7 45

________________________________________________________________________
PROBLEM (7.45) A beam of the cross section shown in Fig. P7.44a is loaded as shown in Fig.
P7.45. Determine:
(a) The shear stress at point E and 40 mm from the top of the beam.
(b) The maximum shearing stress in the beam
SOLUTION
kNRRM BBA 25,0)1(10)1(50)3(20)4(:0 ==+−−=
∑
kNRF Ay 55:0 ==
∑
25 kN/m
45
1 m
A
C
R
A
=55 kN
x
R
B =25 kN
V, kN
-10
2 m
-5
1m
1
m
D
E
-25
10 kN 20 kN
B
Refer to figure in solution of Prob. 7.44:
33
max
46 101.2901022.41 mmQQmI zz ×==×= −
For upper flange:
33
102765.5740120 mmQ ×=××=
(a) 36
63
25 10 (276 10 ) 8.37
41.22 10 (20 10 )
EVQ
M
Pa
Ib
τ
−
−−
××
== =
××
(b) 36
max max
max 63
45 10 (290.1 10 ) 15.84
41.22 10 (20 10 )
VQ
M
Pa
Ib
τ
−
−−
××
== =
××
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