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sm10 134 137

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PROBLEMS (10.134 through 10.137) A beam is supported and loaded as shown in Figs.
P10.134 and P10.137. Determine the maximum deflection between the supports A and B.
SOLUTION (10.134)
P
P
B
A
2a
P/4
C
P/4
M/EI
8a/3
A2
Pa/4EI
E
A1
- Pa/2EI
y
tA/O
a D a
x
a
3
A1 = −
A2 =
θA
x
O
1 Pa 8a
2 Pa 2
( )=−
2 2 EI 3
3 EI
1 Pa 4a
Pa 2
( )=
2 4 EI 3
6 EI
tB/A
vmax
E
B
x
4 a 1 2 a 8a
1
4a
+ ( + )] + A2 [ (a + ]
3 3 3
3
3
3
3
2
3
44 Pa
7 Pa
3 Pa
=−
+
=−
27 EI 54 EI
2 EI
2
1
3 Pa
θ A = − tB / A =
4a
8 EI
3Pa 2 1 Pa x
) x,
θO / A = θO − θ A :
= (
x=a 3
8EI
2 2 EI 2a
1 Pa a 2 ⋅ 3 2
3 Pa 3
] (a 3) =
Thus,
vmax = vO / A = [
↑
2 2 EI 2a 3
4 EI
t B / A = A1[
Continued on next slide
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SOLUTION (10.135)
w
A
a
wa
C
a
B
a
D
5wa/6
7wa/6
M/EI
5wa
x
6 EI
2
5wa /2EI
A1
-wa2/2EI A2
x
wa(x-a) B
M/EI
-wa2/2EI
y
A
A3
C
x
vmax
tA/B
A1 =
θB
B
tB/O
tangent at O
2
at15
B wa 2
1 5watangent
(3a) =
2 2 EI
4 EI
2
1 2wa
2wa 3
A2 = −
(2a ) = −
2 EI
EI
2
3
1 wa
wa
A3 = −
(a) = −
3 2 EI
6 EI
2a
a
57 wa 4
t A / B = A1 (a) + A2 ( ) + A3 ( ) =
3
4
24 EI
3
1
57 wa
θB = tA/ B =
3a
72 EI
1 5
1
θ B / O = θ A − θO 0 = [ wax 2 − wa ( x − a)2 ]
EI
2 8
Thus,
57 3 5
1
wa = wax 3 − wa ( x − a ) 2 ,
72
12
2
x = 1.472a
Then,
vmax = vO = t B / O =
1 5
2x
1
2
( wax 2 ) −
( wa )( x − a )[ ( x − a ) + a ]
2 EI 6
3 2 EI
3
Making x = 1.472a into the above
wa 4
vmax = vO = 0.74
↓
EI
Continued on next slide
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instructional purposes only to students enrolled in courses for which the textbook has been adopted. Any other
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SOLUTION (10.136)
w0
A
a
C
B
a
w0a/2
w0a/2
M/EI
w0a2/2EI
2a/3
A1
C
-w0a2/6EI
A
Cubic
4a/5
x
A2
y
B
A
tA/C
vmax
C
x
tangent at C
w0 a 3
1 w0 a 2
A1 =
(a) =
2 2 EI
4 EI
2
w a3
1 w0 a
A2 = −
(a) = − 0
4 6 EI
24 EI
w a 4 w a 4 2w a 4
2a
4a
t B / A = A1 ( ) − A2 ( ) = 0 − 0 = 0
3
5
6 EI 30 EI 15 EI
2 w0 a 4
vmax = t AC =
↓
15 EI
Continued on next slide
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instructional purposes only to students enrolled in courses for which the textbook has been adopted. Any other
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SOLUTION (10.137)
PL P
B
A
C
L/2
L/2
P/2
3P/2
M/EI
3PL/4EI
3Px/2EI
A1
-PL/4EI
A2
y
tA/D
A
θA
x
B
x
vmax
D
B
x
tB/A
tangent at A
1 3PL L
3 PL2
1 PL L
− PL2
( )=
A2 = −
( )=
2 4 EI 2 16 EI
2 4 EI 2 16 EI
3
L L
L
PL
PL3
5 PL3
t B / A = A1 ( + ) + A2 ( ) =
−
=
2 6
3
8EI 48EI 48 EI
1
5 PL2
θ A = − tB / A = −
L
48 EI
0
θ A/ D = θ A − θD
Also
3Px
3Px 2
θA = −
( x) = −
2 EI
2 EI
5
Equations (1) and (2) yield x =
L
6
Then,
1 3P( 5 L 6) L 5 2 5L
vmax = t A / D = [
L]
2
2 EI
6
3 6
3
3
5 5 PL
PL
=
= 0.0259
↓
432 EI
EI
A1 =
(1)
(2)
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