TRUSSES

SAMPLE QUESTIONS

4 m

4 m

4 m 4 m

4 m

4 m

r=400 mm

16 kN

A

C

D

B

E

F

GH

1. The crane in the figure consists of a planar truss. Determine the forces in members

DE, DG and HG when the crane supports a 16 kN load, indicate whether the members

work in tension (T) or compression (C).

2. Determine the forces in members BC and FG.

CutFBC

FCJ FFJ

FG

3. Determine the forces in members CD, CJ and DJ, state whether they work

in tension (T) or compression (C).

Ax

Ay

T

I. Cut

3 m

FCD

FDJ

FJI

Ax

Ay

T

II. Cut

FCD

FCJ

FKJ

4. The truss shown consists of 45° triangles. The cross members in the two

center panels that do not touch each other are slender bars which are incapable

of carrying compressive loads. Identify the two tension members in these panels

and determine the forces they support. Also determine the force in member MN.

Ax

AyBy

I. Cut

II. Cut

5. Determine the force acting in member DK.

Ux

Uy

Vy

Uy=15 kNVy=20 kN

II. Cut I. CutIII. Cut

IV. Cut

6. Determine the forces in members DE, EI, FI and HI.

4/47

Gx

Ay

I. Cut

Gy

II. Cut

7. Determine the forces in members ME, NE and QG.

I. Cut III. CutII. Cut

20 kN

2 m

2 m

2 m

4 m3 m 3 m 4 m4 m4 m

A

B C D

E F

G

N

M

L K

J

H

P

10 kN6 kN

Radii of pulleys H, F and K 400 mm

4 kN

8. In the truss system shown determine the forces in members EK, LF, FK and CN,

state whether they work in tension (T) or compression (C). Crossed members do not

touch each other and are slender bars that can only support tensile loads.

2 m

2 m

2 m

4 m3 m 3 m 4 m4 m4 m

A

B C D

E F

G

N

M

L K

J

H

P

10 kN6 kN

20 kN

4 kN

10 kN10 kN

10 kN

10 kN

10 kN

Ax

By

Bx

(I) (II)

(III)

(IV)

Radii of pulleys H, F and K 400 mm

9. Determine the forces in members EF, NK and LK.

C

B

A

D E F G

HO

L K JI

N

1 kN

2 kN 2 kN2 kN 5 kN

2 kN 2 kN2 kN

4 m

4 m

3 m 3 m 3 m 3 m

M

3

4

From the equilibrium of whole truss

Ax, Ay and Iy are determined

I. Cut

MH=0

FAB is determined

C

B

A

D E F G

HO

L K JI

N

1 kN

2 kN 2 kN2 kN 3 kN

4 kN

2 kN 2 kN2 kN

4 m

4 m

3 m 3 m 3 m 3 m

I. Cut

Top Part

Ay Iy

M

Ax

FHI

FHOFMOFMNFBN

FBA

II. Cut

MM=0

FEF and FMF are determined

C

B

A

D E F G

HO

L K JI

N

1 kN

2 kN 2 kN2 kN 3 kN

4 kN

2 kN 2 kN2 kN

4 m

4 m

3 m 3 m 3 m 3 m

II. Cut

Top Part

M

FEF

FMF

FMOFMNFBN

FBA

III. Cut

MN=0

FLK and FNK are determined

C

B

A

D E F G

HO

L K JI

N

1 kN

2 kN 2 kN2 kN 3 kN

4 kN

2 kN 2 kN2 kN

4 m

4 m

3 m 3 m 3 m 3 m

III. Cut

Left Side

MFMO

FLK

FNK

FMF

FEF

10. Determine the forces in members KN, FC and CB.

kN

kN

kN

kN

kN

1 m

1 m

1 m

2 m

2 m1 m1 m2 m

A B

C D

O

E

G

P F

NM

I

JK

L

H

225

225

220

210 210

Forces in KN, FC and CB.

kN

kN

kN

kN

kN

1 m

1 m

1 m

2 m

2 m1 m1 m2 m

A B

C D

O

E

G

P F

NM

I

JK

L

H

225

225

220

210 210

I. Cut

II. Cut

III. Cut

IV. Cut

ByAy

Ax