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1. Determine the forces in members CG and GH of the symmetrically loaded
truss. Indicate whether the members work in tension {T} or compression {C}.
(4/34)
Fy
FBD of whole system
Ay
Ax=0
0 AM LFFLFL
LL yyy 5.1,1015,0)10()10(2
)7()3( +
LALLAFAF yyyxx 5.1035.10,00
FCD
FCG
FHG
Fy Ay
Ax=0
Cut, right side 0 CM
CG and GH
0)7(5.1)7(2
)4()3( LL
LFGH TLFGH +
0 yF
0
05.12
)53
(
CG
CG
F
LL
LF
Cut
CG and GH = ?
2. Determine the force in member DG of the loaded truss.
TLF
FF
F
DG
DGGH
y
004.14sin
0
FDC
FBD of whole system
0 BM+
Cut Ay
Bx=0
By
LAALALLLLL yyy 3,2060,0)20()20()16()12()8()4(
Cut, left side 0 DM+
LF
LLLF
GH
GH
12.4
0)8(3)8()4()3(04.14cos
FGH
FFG
FDG
Joint G
FDH
FGH
y
x q
04.14,41
tan qq
DG = ?
3. Determine the forces in members BC and FG. (4/41)
BC and FG
Cut FBC
FCJ FFJ
FFG
TNF
F
M
BC
BC
F
600
0)2(1200)4(
0
Cut, upper side
+
CNF
F
M
BC
FG
C
600
0)2(1200)4(
0
+
4. The hinged frames ACE and DFB are connected by two hinged bars, AB and
CD which cross without being connected. Compute the force in AB. (4/47)
AB and CD cross without being connected. AB=?
ABCD
CDAB
CDCDABAB
FF
FF
FFFF
99.2
99.195.5
0)3(sin)4(cos)5.1(sin)6(cos
0 EM+
I. Cut, left side
7.29,5.3
2tan
FAB
I.Cut
FCD
Ex
Ey
TkNF
CkNF
FF
FF
FF
FF
CD
AB
ABAB
AB
F
CD
ABAB
CDCD
AB
33.11
79.3
6099.179.17
99.16095.5
0)6(10)3(sin)4(cos
)5.1(sin)6(cos
99.2
0 FM+
II. Cut, right side
D
C
3.5 m
2 m
FAB
FCD
Fy
Fx
II.Cut
5. In the planar truss shown, the crossed members in the center panel which cross without touching are slender tie rods incapable of supporting compression. Determine whether member DH or GE works in tension. Also determine the forces in members JI, JE, and EK. State whether they work in tension {T} or compression {C}.
A
B C D E F
G H
I
J
4 m 4 m 4 m
5 m
4 m
5 m
K
4 m
L
12 kN
8 kN
10 kN 20 kN
Determine whether member DH or GE works in tension. Also determine the forces in members JI, JE, and EK.
A
B C D E F
G H
I
J
4 m 4 m 4 m
5 m
4 m
5 m
K
4 m
L
12 kN
8 kN
10 kN 20 kN
6. Find the force in member JQ for the Baltimore truss where all angles are
30°, 60°, 90° or 120°. Indicate whether the member works in tension {T} or
compression {C}. (4/55)
JQ = ?, all angles are 30°, 60°, 90° or 120°
NN=125 kN NA=75 kN
a
1.73a
1.73a
3.46a
JQ=? All angles are 30°, 60°, 90° or 120°
0 GM+
CkNFaaaaF WXWX 130,0)6(125)2(100)(100)46.3(
I. Cut, right side
FWX
NN=125 kN
FQX
NA=75 kN
1.73a
1.73a FGQ
FGH
FWX
FJQ
FHJ
0 GM+
CkNF
aaaFaF
JQ
JQWX
85.57
0)6(125)2(100)2(60sin)46.3(
II. Cut, right side
I.Cut
II.Cut
7. Determine the forces acting in members GE, HI and DI in the truss loaded as shown. State whether they work in tension {T} or compression {C}.
.
3
4 5 kN
C
D
J I
4 kN
R=0.4 m
4 m
4 m
3
4 5 kN
C
D
J I
4 kN
R=0.4 m
4 m
4 m
GE, HI, DI = ?
4 m
A B
D
C
H G F
E
K J I L
N M P
4 m 4 m 4 m
3 m
3 m
3 m
20 kN
3 kN
5 kN
10 kN 5 kN
4 kN
3 kN
8. Determine the force acting in member JI for the truss shown. Indicate
whether the member works in tension {T} or compression {C}.
4 m
A B
D
C
H G F
E
K J I L
N M P
4 m 4 m 4 m
3 m
3 m
3 m
20 kN
3 kN
5 kN
10 kN 5 kN
4 kN
3 kN
JI=?
9. Determine the forces in members ON, NL and DL.
Ax
Ay Iy
kNIIAF
kNAAM
kNAF
yyyy
yyA
xx
60100
40)3(2)6(2)9(4)15(2)2(6)18(0
60
From equilibrium of whole truss;
FON
FOC
FBC
I.cut
I.cut left side
CkNF
FFAM
ON
ONON
kN
yC
014.9
0)3(64
62
64
4)3(2)2(6)6(0
2222
4
Ax
Ay
Iy
+
Joint M
4 kN
FML FMN
)(605.3064
4240
064
6
64
60
22
2222
CkNFFFF
FFFFF
MLMNMNy
MLMNMLMNx
Ax
Ay
Iy
II.cut
FMN
FNL
FDL
FDE
)(0054
64
420
5.4
0)4(464
63
64
4)2(6)6(2)9(0
22
22
605.3
22
605.34
memberforceZeroFFFAF
CkNF
FFFAM
DLDLMNyy
NL
NLMNMN
kN
yD
II.cut
Ax
Ay
Iy
+
20 kN
10. Determine the forces in members HG and IG.
20 kN
I.cut
II.cut
20 kN
20 kN 20 kN
20 kN
20 kN
20 kN
forces in members HG and IG
20 kN
I.cut
II.cut
FCD
20 kN
20 kN 20 kN
20 kN
20 kN
20 kN
FHG
FGI FGJ
I.cut MG=0 FCD=54.14 kN (T)
II.cut MA=0 FHG=81.21 kN (C) I.cut Fx=0 FIG=18.29 kN (T)
FCD
FHG
FHI FBA
forces in members HG and IG
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