Fundamentals of Structural Analysis
1. In structural analysis, what is the sum of forces in a static equilibrium system?
A. Zero
B. Equal to the moment
C. Equal to the applied force
D. Infinity
Answer: A
Explanation: A structure in static equilibrium must satisfy ΣF = 0 and ΣM = 0.
2. What is the modulus of elasticity (E) of concrete commonly used in reinforced concrete design?
A. 21,000 MPa
B. 2,100 MPa
C. 200,000 MPa
D. 1,000 MPa
Answer: A
Explanation: The modulus of elasticity of concrete varies with strength, but typical values range from 20,000 MPa to 25,000 MPa.
3. A simply supported beam carries a uniform load. Where does the maximum bending moment occur?
A. At the support
B. At midspan
C. At one-third the length
D. At quarter-span
Answer: B
Explanation: For a simply supported beam with uniform loading, the maximum bending moment occurs at the midpoint.
4. What is the main purpose of using shear reinforcement in beams?
A. To resist tensile stresses
B. To reduce bending moment
C. To prevent shear failure
D. To increase stiffness
Answer: C
Explanation: Shear reinforcement (stirrups) is used to prevent diagonal tension cracks due to shear forces
5. The moment of inertia (I) is a measure of:
A. Shear stress
B. Bending resistance
C. Axial force capacity
D. Slenderness ratio
Answer: B
Explanation: The moment of inertia quantifies a beam's resistance to bending under applied loads.
6. What is the primary factor affecting deflection in beams?
A. Modulus of elasticity
B. Shear force
C. Load duration
D. Density of material
Answer: A
Explanation: Deflection is directly related to the modulus of elasticity and moment of inertia (I) of the beam.
7. The centroid of a rectangular section is located at:
A. The topmost edge
B. The bottommost edge
C. The geometric center
D. The midpoint of the base
Answer: C
Explanation: The centroid of a rectangular cross-section is at its geometric center.
8. A structure is statically determinate if:
A. The number of reactions equals the number of equilibrium equations
B. The bending moment is zero everywhere
C. The structure has at least one redundant support
D. The structure has no external loads
Answer: A
Explanation: A statically determinate structure can be solved using only the equations of equilibrium.
9. What is the standard unit of stress in the SI system?
A. Newton
B. Pascal
C. Joule
D. Watt
Answer: B
Explanation: Stress is force per unit area, measured in Pascals (Pa = N/m²).
10. The effective length of a column depends on:
A. Load type
B. End conditions
C. Column diameter
D. Material strength
Answer: B
Explanation: The effective length factor varies depending on the boundary conditions of the column.
Design of Structural Elements
11. The purpose of stirrups in reinforced concrete beams is to:
A. Provide bending resistance
B. Increase ductility
C. Reduce column buckling
D. Resist shear forces
Answer: D
Explanation: Stirrups are placed to resist shear and prevent diagonal cracks.
12. A truss structure is considered stable if:
A. It has fewer than three supports
B. The number of members follows the rule m = 2j - 3
C. All joints are fixed
D. The deflection is zero
Answer: B
Explanation: A stable truss satisfies the relation m = 2j - 3, where m is members and j is joints.
13. In column design, the slenderness ratio affects:
A. Shear strength
B. Bending moment
C. Buckling capacity
D. Tensile strength
Answer: C
Explanation: A high slenderness ratio increases the likelihood of buckling.
14. The primary material used in steel reinforcement for concrete is:
A. Stainless steel
B. Copper
C. Aluminum
D. Carbon steel
Answer: D
Explanation: Carbon steel is widely used due to its high tensile strength and durability.
15. A column fails due to excessive:
A. Shear stress
B. Buckling
C. Bending moment
D. Torsion
Answer: B
Explanation: Columns primarily fail due to buckling under compressive loads.
Principles of Reinforced Concrete and Steel Structures
16. The nominal cover in reinforced concrete is provided to:
A. Improve load distribution
B. Protect reinforcement from corrosion
C. Reduce shrinkage
D. Increase flexural strength
Answer: B
Explanation: Cover protects steel from corrosion and fire.
17. The allowable stress design (ASD) method ensures:
A. Safety by applying factors of safety
B. Strength by using ultimate loads
C. Elastic behavior of materials
D. Zero deformation
Answer: A
Explanation: ASD applies safety factors to ensure structure safety under expected loads.
18. A beam is considered under-reinforced if:
A. It has excessive reinforcement
B. It fails by concrete crushing
C. It has reinforcement below balanced conditions
D. The stirrups exceed shear demand
Answer: C
Explanation: Under-reinforced beams fail by yielding of steel, a desirable mode of failure.
19. The primary function of steel reinforcement in concrete structures is to:
A. Withstand tensile forces
B. Provide shear resistance
C. Reduce deflection
D. Increase compressive strength
Answer: A
Explanation: Concrete is strong in compression but weak in tension, requiring reinforcement.
20. In reinforced concrete design, the balanced reinforcement ratio means:
A. The failure occurs by crushing of concrete and yielding of steel simultaneously
B. The structure has no reinforcement
C. The reinforcement exceeds the design limit
D. The concrete fails before steel yields
Answer: A
Explanation: A balanced section means both concrete and steel reach their ultimate strengths simultaneously.
21. The primary reason for using doubly reinforced beams is:
A. To increase shear strength
B. To resist high moments in limited depth
C. To reduce deflections completely
D. To enhance column interaction
Answer: B
Explanation: When depth restrictions prevent a singly reinforced beam from resisting the moment, a doubly reinforced section is used.
22. What is the function of transverse reinforcement in columns?
A. Increase axial capacity
B. Improve lateral stability
C. Confine concrete and prevent buckling of longitudinal bars
D. Reduce torsional effects
Answer: C
Explanation: Transverse reinforcement (ties or spirals) helps prevent buckling of longitudinal bars and increases ductility.
23. In steel structures, lateral-torsional buckling occurs in:
A. Short columns
B. Long beams under bending
C. Axially loaded members
D. Shear walls
Answer: B
Explanation: Beams with insufficient lateral support can experience lateral-torsional buckling.
24. Which of the following is a failure mode in reinforced concrete beams?
A. Yielding of reinforcement
B. Crushing of concrete in compression
C. Shear failure due to diagonal cracks
D. All of the above
Answer: D
Explanation: Beams can fail due to multiple mechanisms, including yielding, crushing, and shear failure.
25. A fully fixed beam will have how many reaction components?
A. 2
B. 3
C. 4
D. 6
Answer: D
Explanation: A fixed beam has two forces and one moment at each end (total of 6 reactions).
26. What is the main reason for using composite beams in steel structures?
A. Reduce self-weight
B. Improve corrosion resistance
C. Increase load-bearing capacity by utilizing both steel and concrete
D. Allow for easier connections
Answer: C
Explanation: Composite beams combine steel and concrete to enhance strength and stiffness.
27. When designing foundations for sanitary structures, what type of load is most critical?
A. Wind load
B. Earthquake load
C. Hydrostatic uplift
D. Temperature load
Answer: C
Explanation: Sanitary structures, such as water tanks and treatment plants, must resist hydrostatic uplift from groundwater pressure.
28. What is the primary concern in designing water-retaining structures?
A. Shear capacity
B. Crack control to prevent leakage
C. Bending strength
D. Fatigue resistance
Answer: B
Explanation: Cracks in water-retaining structures can lead to leakage, requiring careful reinforcement detailing.
29. In earthquake-resistant design, ductility is crucial because:
A. It prevents elastic deformation
B. It eliminates the need for reinforcement
C. It reduces self-weight of the structure
D. It allows structures to absorb and dissipate energy
Answer: D
Explanation: Ductility helps structures deform plastically during earthquakes without sudden failure.
30. The term “serviceability limit state” in structural design refers to:
A. The structure's ability to carry ultimate loads
B. The structure's performance under normal operating conditions without excessive deflection or cracking
C. The failure point of materials used
D. The moment when reinforcement begins yielding
Answer: B
Explanation: Serviceability limit states ensure structures perform adequately without excessive deformations or vibrations.