Structural Analysis Questions and Answers - Space Trusses

1. If B=6, R=7 and J= 4, then the truss are:-
a) statically determinate
b) statically indeterminate
c) stable
d) unstable

Answer: b
Explanation: B + R = 13 > 3*J. So, truss is statically indeterminate. Without further insight, we can’t predict stability.

2. If B=6, R=5 and J= 4, then the truss is:-
a) statically determinate
b) statically indeterminate and stable
c) stable
d) unstable

Answer: d
Explanation: B + R = 11 < 3*J. So, the truss will be unstable.

3. The external stability of the space truss requires that the support reactions keep the truss in force equilibrium about all the axes.
a) True
b) False

Answer: b
Explanation: They require moment equilibrium about all the axes as well.

4. What is the degree of freedom of space roller joint?
a) 0
b) 1
c) 2
d) 3

Answer: b
Explanation: It can move along a slot in the base plane

5. According to assumptions, which type of joints are used in space truss?
a) pin joint
b) ball and socket joint
c) fixed joint
d) roller joint

Answer: b
Explanation: To treat every member of a space truss as axial- force members, every joint is assumed to be of ball & socket type.

6. How many reaction forces are involved in a short link type of joint?
a) 1
b) 2
c) 3
d) 4

Answer: a
Explanation: One force is unknown which acts in line with the link.

7. How many reaction forces are involved in a roller type of joint?
a) 1
b) 2
c) 3
d) 4

Answer: a
Explanation: One unknown force acts perpendicular to the plane of roller

8. The degree of freedom for the vertical guided roller is ________
a) 0
b) 1
c) 2
d) 3

Answer: b
Explanation: Vertical guided roller resists horizontal/axial force and bending moment. However, it cannot resist vertical forces as it slides down along the plane. Hence it has 1 degree of freedom.
q138

9. What is kinematic indeterminacy for the given figure considering axial deformation?
q139
a) 0
b) 2
c) 4
d) 6

Answer: c
Explanation: The given beam is supported by roller support at both of its ends. Roller support, if considering axial deformation has two degrees of freedom i.e. Rotation and Horizontal sway. Therefore, the degree of freedom of the beam is 4.

10. What is kinematic indeterminacy for the given figure without considering axial deformation?
q139
a) 0
b) 2
c) 4
d) 6

Answer: b
Explanation: The given beam is supported by roller support at both of its ends. Roller support, if not considering axial deformation has one degree of freedom i.e. Rotation. Therefore, the degree of freedom of the beam is 2.