# Structural Analysis Questions and Answers – Trusses Static Indeterminacy

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This set of Structural Analysis Multiple Choice Questions & Answers (MCQs) focuses on “Trusses Static Indeterminacy”.

1. Statically indeterminate structure requires _______
a) Equilibrium Conditions Only
b) Compatibility Conditions Only
c) Equilibrium and Compatibility Condition together
d) Cannot be solved analytically

Explanation: Determination of unknown forces or reactions in statically indeterminate structure requires Equilibrium and Compatibility Condition together.

2. Indeterminate structures are economical than determinate structure.
a) True
b) False

Explanation: Bending Moment is less in indeterminate structure as compared to determinate structure for the same set of loadings. Thus, lower bending moment value requires lesser depth of sections which ultimately reduces the cross sectional area of the structure. Hence, indeterminate structure are more economical than determinate structure.

3. To convert indeterminate structure to a determinate structure, number of force release to be provided equals to _______
a) Number of equilibriums equations for the respective structures available
b) External Static Indeterminacy only
c) Internal Static Indeterminacy only
d) Static Indeterminacy

Explanation: To convert indeterminate structure to a determinate structure, Number of force releases to be provided equals to the static indeterminacy of the structure.

4. The following structure is _________ a) Stable
b) Statically Unstable
c) Geometrically Unstable
d) Internally Unstable

Explanation: The above structure is unstable as the minimum reactions for existence of the structure is 3. The reaction for roller support is 1, thus total reaction is (1+1) = 2. Hence, above structure is statically unstable.

5. The following structure is _______ a) Stable
b) Statically Unstable
c) Geometrically Unstable
d) Internally Unstable

Explanation: The following structure has minimum three reaction required for statically stability, it has no concurrent reactions and thus it is geometrically stable. But the given has three internal hinges and thus it is internally unstable.

6. The following structure is ________ a) Stable
b) Statically Unstable
c) Geometrically Unstable
d) Internally Unstable

Explanation: The following structure has minimum three reaction required for statically stability, it has no concurrent reactions and thus it is geometrically stable. It regains its original position if laterally displaced. Hence, it’s a stable structure.

7. Static Indeterminacy for pin jointed plane frame is given by ________
a) (m + r) – 2j
b) (m + r) – 3j
c) (3m + r) -3j
d) (6m + r) – 6j

Explanation: Static Indeterminacy for plane jointed plane frame is given by (m + r) -2j. Here, m – no of member, r – number of reaction, j – number of joints.

8. Force releases by Vertical Shear Hinge is _______ a) Number of member – 1
b) 3*(Number of member-1)
c) 2
d) 1

Explanation: The number of force release for vertical hinge is 1. The only force release in vertical hinge is shear force.

9. Force releases by Link is _______ a) Number of member – 1
b) 3*(Number of member-1)
c) 2
d) 1

Explanation: Links can carry axial force only. Links cannot carry or transfer shear force and bending Moment. Therefore, force releases for links is 2.

10. Which of the option is correct for mechanism in truss?
a) M = 2J – 3
b) M < 2J -3
c) M > 2J – 3
d) Over stiff truss is example of mechanism in truss 