Structural Analysis Questions and Answers – Determinacy and Stability

This set of Structural Analysis Multiple Choice Questions & Answers (MCQs) focuses on “Determinacy and Stability”.

1. For the validity of principle of superposition, materials should behave in which manner?
a) linear-elastic
b) non-linear-elastic
c) Non-linear- inelastic
d) Linear- inelastic
View Answer

Answer: d
Explanation: They should behave in a linear elastic manner so that, Hooke’s law is valid.

2. If in planar system, X parts/members are there with Y no. of forces, then condition for statically determinacy is:-
a) Y < 3X
b) Y > 3X
c) Y = 3X
d) None of the mentioned
View Answer

Answer: c
Explanation: There can be at max. 3 equilibrium equations for each part.

3. If Y > 3X (X and Y are from the above question) then, the system is:-
a) Statically indeterminate
b) Statically determinate
c) Can’t say
d) Depends on other conditions
View Answer

Answer: a
Explanation: As there can be at max. 3X equations, at least one of the forces will be unsolvbale.
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4. If in a planar system, only 2 reaction forces are acting, then the system is:-
a) Essentially unstable
b) Essentially stable
c) Can’t say
d) None of the mentioned
View Answer

Answer: a
Explanation: If no. of reactions is less than 3 in any planar system, then the system is essentially unstable.

5. If all the reactions acting on a planar system are concurrent in nature, then the system is:-
a) Can’t say
b) Essentially stable
c) Essentially unstable
d) None of the mentioned
View Answer

Answer: c
Explanation: The system can rotate about the point of concurrency. So, it is essentially unstable.
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6. If 4 reactions are acting on a beam, then the system is:-
a) Unstable & indeterminate
b) Stable & indeterminate
c) Stable & determinate
d) Can’t say
View Answer

Answer: d
Explanation: 4 reactions mean that the system is definitely indeterminate. But stability would depend upon the nature of forces acting on the planar structure.

7. If a system has more equations of equilibrium than no. of forces, then the system is:-
a) Improperly constrained
b) Partially constrained
c) Stable
d) Solvable
View Answer

Answer: b
Explanation: In these cases, system is unstable and unsolvable and is termed as partially constrained.
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8. How many cases out of the following are improperly constrained?
Parallel forces, concurrent forces, perpendicular forces, only moment
a) 1
b) 2
c) 3
d) 4
View Answer

Answer: b
Explanation: parallel and concurrent are improperly constrained.

9. If a structure has total 10 joints, then what should be the minimum no. of joints in which equilibrium equations should be concurrently satisfied for stability?
a) 7
b) 8
c) 9
d) 10
View Answer

Answer: d
Explanation: For stability, equilibrium equations should be satisfied concurrently at each and every joint of the structure.
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10. If a structure has 2j – r no. of members, then it will be:-
a) stable
b) unstable
c) depends upon structure
d) depends upon magnitude of load
View Answer

Answer: c
Explanation: In these cases, structures can be stable as well unstable.
Here, j represent no. of joints and r represents no. of external forces.

11. If a truss consists of a non-triangular element, then it will essentially be unstable.
State whether the above statement is true or false.
a) true
b) false
View Answer

Answer: b
Explanation: In these cases, instability is the most probable occurrence, but there are a lot of examples which are unstable.

Sanfoundry Global Education & Learning Series – Structural Analysis.

To practice all areas of Structural Analysis, here is complete set of 1000+ Multiple Choice Questions and Answers.

If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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