Free Structural Analysis MCQs with Answers
78 Structural Analysis MCQs from Civil Engineering, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Structural analysis determines how beams, frames, trusses and arches carry loads through reactions, shear forces, bending moments, axial forces and deflections. It covers free-body diagrams, equilibrium equations, determinacy, influence lines and methods such as slope deflection, moment distribution and virtual work, while distinguishing analysis of a structure from its design.
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78 questions · page 4 of 4
- A. It is symmetric about its main diagonal
- B. It contains only positive off-diagonal terms
- C. It remains unchanged after removing a support
- D. It has identical values in every row
Explanation: Reciprocity makes the stiffness coefficient Kij equal to Kji, so the global stiffness matrix is symmetric.
Correct answer: It is symmetric about its main diagonal- A. Force at coordinate i due to unit displacement at j
- B. Displacement at coordinate i due to unit force at j
- C. Rotation at coordinate j due to unit moment at i
- D. Moment at coordinate i due to unit rotation at j
Explanation: The coefficient fij is the displacement at coordinate i caused by a unit force applied at coordinate j.
Correct answer: Displacement at coordinate i due to unit force at j63. For a prismatic column fixed at one end and free at the other, the Euler critical buckling load is
- A. π²EI divided by L²
- B. π²EI divided by 2L²
- C. π²EI divided by 4L²
- D. 4π²EI divided by L²
Explanation: A fixed-free column has an effective length of 2L. Substituting this into Euler's formula gives Pcr = π²EI divided by 4L².
Correct answer: π²EI divided by 4L²- A. Uniform transverse pressure
- B. Bending moment only
- C. Shear force and torsion
- D. Axial force only
Explanation: Ideal truss members are connected by frictionless pins and loads act at the joints, so each member behaves as a two-force member.
Correct answer: Axial force only- A. A vertical force only
- B. A horizontal force only
- C. A moment and horizontal force
- D. A moment and vertical force
Explanation: A smooth roller on a horizontal surface resists motion normal to the surface, giving a vertical reaction.
Correct answer: A vertical force only- A. wL at each end
- B. wL divided by 2 at each end
- C. wL divided by 4 at each end
- D. wL divided by 12 at each end
Explanation: The total distributed load is wL, and symmetry divides it equally between the two end shear forces.
Correct answer: wL divided by 2 at each end67. For an undamped single degree of freedom system, resonance occurs when the excitation frequency is
- A. Much lower than the natural frequency
- B. Twice the damping frequency only
- C. Equal or very close to the natural frequency
- D. Independent of the natural frequency
Explanation: Resonance occurs when the forcing frequency approaches the system's natural frequency.
Correct answer: Equal or very close to the natural frequency- A. √(k/m)
- B. 2k divided by m
- C. k divided by 2m
- D. 2√(km)
Explanation: The critical damping coefficient is cc = 2√(km). A value below this gives an underdamped response, while a value above it gives an…
Correct answer: 2√(km)- A. It must satisfy the essential support conditions
- B. It must satisfy equilibrium at every internal point
- C. It must contain no bending deformation
- D. It must be identical to every higher mode
Explanation: Rayleigh's method uses an assumed deflected shape that must satisfy the essential, or geometric, boundary conditions.
Correct answer: It must satisfy the essential support conditions- A. The identity matrix only
- B. The mass matrix
- C. The load vector
- D. The support reaction matrix
Explanation: Distinct normal modes of an undamped linear structure satisfy mass orthogonality, and also stiffness orthogonality under the usual…
Correct answer: The mass matrix- A. A straight line
- B. A parabolic curve
- C. A cubic curve
- D. A rectangular curve
Explanation: A linearly varying load produces a parabolic shear diagram after integration.
Correct answer: A cubic curve- A. Their lines of action are equally spaced
- B. Their lines of action are perpendicular
- C. Their magnitudes are identical
- D. Their lines of action are concurrent
Explanation: For three nonparallel coplanar forces to have zero resultant moment, their lines of action must meet at one point.
Correct answer: Their lines of action are concurrent- A. Both translations and rotation
- B. Vertical translation and rotation
- C. Horizontal translation only
- D. Rotation only
Explanation: A fixed support prevents horizontal movement, vertical movement, and rotation of the connected member end.
Correct answer: Both translations and rotation- A. The three forces are equal
- B. The three forces are concurrent
- C. The three forces are perpendicular
- D. The three forces have equal moments
Explanation: Taking moments about the intersection of any two force lines shows that the third force line must pass through the same point.
Correct answer: The three forces are concurrent- A. Bending only
- B. Compression only
- C. Tension only
- D. Torsion only
Explanation: A flexible cable has negligible bending and flexural stiffness, so it carries axial tension along its changing shape.
Correct answer: Tension only- A. To prescribe the applied loading direction
- B. To calculate material density directly
- C. To eliminate support reactions
- D. To interpolate displacement within the element
Explanation: Shape functions express displacement at an interior point in terms of the element's nodal displacement degrees of freedom.
Correct answer: To interpolate displacement within the element- A. Constant or linear
- B. Parabolic only
- C. Cubic only
- D. Sinusoidal only
Explanation: With no distributed load, the shear force is constant between point actions, so the bending moment varies linearly.
Correct answer: Constant or linear- A. A stable elastic frame
- B. A kinematic mechanism
- C. A zero-shear section
- D. A statically determinate span
Explanation: A plastic hinge allows rotation at the plastic moment, and a sufficient number of such hinges can convert the structure into a mechanism.
Correct answer: A kinematic mechanism