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sm10 154

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PROBLEM (10.154) A propped cantilever beam AB is subjected to loads as shown in Fig. P10.154.
Calculate the reactions at each support.
SOLUTION
5 kN/m
10 kN
MB
A
B
C
RA
M/EI
A1
A2
M/EI
A3
Parabolic
Spandrel
Select RA as redundant.
Draw
M EI diagrams (see Table A.4).
10 RA
50 RA
1 10 RA
A1 = (
)(10) =
2 EI
EI
1 80
320
A2 = − ( )(8) = −
x
2 EI
EI
1 90
180
A3 = − ( )(6) = −
-80
3 EI
EI
Place reference tangent at B:
x θ B = 0. Also
2
2
t A B = A1[ (10)] + A2 [ (8) + 2]
-90
3
3
1
+ A3 [10 − (6)] = 0
4
RB
Then
tA B =
50 RA 20 320 28 180
( )−
( )−
(8.5) = 0
EI 3
EI 3
EI
or
RA = 13.55 kN ↑
Equilibrium:
RB = 10 + 30 − 13.55 = 26.45 kN ↑
M B = 34.5 kN ⋅ m
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