# Strength of Materials Questions and Answers – Design of Columns

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This set of Strength of Materials Multiple Choice Questions & Answers (MCQs) focuses on “Design of Columns”.

1. Eccentrically loaded columns have to be designed for combined axial and ________
a) Shear force
b) Bending moments
c) Torsion
d) Creep

Explanation: When the line of action of the resultant force doesn’t coincide with the axis of centre of gravity then it is called eccentrically loaded column. An eccentrically loaded column has to be designed for combined axial force and bending moments.

2. What is the recommended value of effective length if the column is effectively held in position and fixed against rotation in both ends?
a) 0.8 l
b) 0.5 l
c) 0.65 l
d) 0.9 l

Explanation: Effectively held in position and fixed against rotation in both ends is 0.65 l.

 End Positions Of a Column Value of effective length Effectively held in position and fixed against rotation in both ends 0.65 × l Effectively held in position at both ends but not restrained against rotation 1.00 × l

3. What is the minimum value of eccentricity provided in columns?
a) 50 mm
b) 20 mm
c) 30 mm
d) 45 mm

Explanation: No column can have a perfectly axial load. There may be some moments acting due to imperfection of construction or due to actual conditions of loading. Hence IS 456 -2000, recommend eccentricity of 20 mm.

4. The strength of the column with helical reinforcement shall be ____ times the strength of similar column with lateral ties.
a) 2.0
b) 1.05
c) 3
d) 1.5

Explanation: The strength of column with helical reinforcement Shall be 1.05 times the strength of similar column with lateral ties, provided the ratio of the volume of helical reinforcement to the volume of the core shall not be less than 0.36(Ag/Ak – 1) fck/fy.

5. The minimum diameter provided for the longitudinal bars is ________
a) 15 mm
b) 20 mm
c) 12 mm
d) 18 mm

Explanation: The minimum diameter of the longitudinal bars provided in the column is 12 mm and the spacing of longitudinal bars measured along the periphery of the column shall not exceed 300 mm.
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6. What is the minimum number of longitudinal bars provided in the rectangular column?
a) 4
b) 5
c) 6
d) 8

Explanation: According to IS 456-2000, clause 26.5.3, the minimum number of longitudinal bars to be provided is 4 for rectangular columns and the minimum number of longitudinal bars to be provided for circular columns is 6.

7. The ends of ________ shall be properly anchored.
a) Longitudinal reinforcement
b) Transverse reinforcement
c) Torsional reinforcement
d) Shear reinforcement

Explanation: The effective lateral support is given by transverse reinforcement either in the form of circular rings or by lateral ties. The ends of transverse reinforcement shall be properly anchored.

8. For longitudinal reinforcing bar, the nominal cover should not be less than ___________
a) 30 mm
b) 20 mm
c) 40 mm
d) 50 mm

Explanation: According to IS 456-2000, clause 26.4.2.1, the nominal cover for longitudinal reinforcing bars in any case shall not be less than 40 mm or less than the diameter of such bar.

9. Which of the following reservoirs is also known as ___________
a) Ground service reservoirs
b) Elevated reservoirs
d) Storey reservoirs

Explanation: Ground service reservoirs are constructed at ground level and mainly used to store water. They are generally constructed with masonry (or) RCC slab. These are also known as surface reservoirs or not elevated reservoirs.

10. A system in which water is supplied only for fixed few hours, such system is called ____
a) Closed
b) Intermittent
c) Combined
d) Lift

Explanation: In the intermittent system, the water is supplied only for a few hours the system is adopted when adequate water from the source is not available. The system is widely adopted by much local water authority it is functioned through phases.

11. In ___________ system, air relief valves are not required.
a) Gravity
b) Intermittent
c) Continuous
d) Grid

Explanation: In the continuous system, the supply of water is 24 hours a day. This is the most ideal system and is adopted when plenty of water is available. As the water doesn’t get contaminated and circulating at uniform pressure, air relief valves are not required essentially.

12. Which of the following is one of the layouts of distribution systems?
a) Dual system
b) Gravity system
c) Grid Iron system
d) Pressure system

Explanation: In grid iron systems, there are no dead ends hence stagnation of water and its consequences are eliminated. The water is kept in good circulation due to the absence of dead ends. The system is suitable for well planned towns.

13. Which of the following system is also known as an interlaced system?
a) Tree system
b) Grid iron system
c) Circle system

Explanation: Grid iron system is an improvement over the tree system. In the system, the mains, sub lines and branches are interconnected with each other. This system is also known as interlaced or reticulation system.

14. Which of the following is also known as a ring system?
a) Circle
b) Reticulation
d) Interlaced

Explanation: In a circle system, the entire locality is divided into either rectangular (or) circular blocks. The water mains are laid along the peripheral roads with sub mains branching out from mains. This system is also known as ring system.

15. Varignon’s theorem is called as _________
a) Principle of Forces
b) Principle of moments
c) Principle of points
d) Theory of couple

Explanation: Varignon’s theorem states that “the moment of a force about any point is equal to the sum of moments of the components about the same point”. This principle is also known as the principle of moments.
R.r = P.p + Q.c
Where P, Q are forces and R is resultant.
“c” is the perpendicular distance of Q.

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