RCC Questions (R7)

In this post, I will share some important questions which are frequently asked in competitive examinations such as SSC, UPSC and state PSCs.



  1. The main reinforcement of an RC slab consists of 10 mm bars at 10 cm spacing. If it is desired to replace 10 mm bars by 12 mm bars, then the spacing of 12 mm bars should be


    1. 12 cm
    2. 14 cm
    3. 14.40 cm
    4. 16 cm

    View Answer
    Answer: c
    This question was asked in IES [95].
    Let's say the spacing of 10 mm bar is $x$ and that of 12 mm bar is $y$

    $\frac{1}{x} \times \text{area of 10 mm bar} = \frac{1}{y} \times \text{area of 12 mm bar}$

    $y= \frac{\pi \times 12^2/4}{\pi \times 10^2 /4} \times 10 = 14.40 cm$

  2. Torsion resisting capacity of a given RCC section


    1. Decreases with the decrease in stirrups spacing
    2. Decreases with the increase in longitudinal bars
    3. Does not depend upon stirrup and longitudinal steel
    4. Increases with the increase in the stirrup and longitudinal steel

    View Answer
    Answer: d
    This question was asked in IES [95].
    An increase in the area of stirrups and longitudinal bars increases the stiffness of RCC section and therefore, the torsion resistance capacity of the section increases.

  3. The one-way slab is designed ...


    1. as a beam whose width is equal to the shorter span of the slab
    2. as a beam of unit width
    3. by using Marcus' Method
    4. Any of the above

    View Answer
    Answer: b

  4. Which of the following method is used to design a 2-way slab simply supported on the four edges with corners not held down and carrying UDL?


    1. Grashoff-Rankine Method
    2. Pigeaud's Method
    3. Marcus' Method
    4. None of the above

    View Answer
    Answer: a

  5. The deflection in a two-way slab as compared to the one-way slab is ...


    1. equal
    2. much smaller
    3. much larger
    4. a little less

    View Answer
    Answer: b

  6. As per IS 456, the length of the middle strip of a two-way slab is ...


    1. 1/2 of the span
    2. 1/3 of the span
    3. 3/4 of the span
    4. 2/3 of the span

    View Answer
    Answer: c
    As per IS 456, Fig 25, It is 3/4 of the span.

  7. In case of 2-way slab, the limiting deflection of the slab is ...


    1. primarily a function of the long span
    2. primarily a function of the short span
    3. independent of the long or short span
    4. dependent on both long and short spans

    View Answer
    Answer: b
    This question was asked in IES [95]
    As per IS 456, Cl 24.1 [Note], the short span is used to calcuate depth/effective depth ratio. From this, we can say that in a 2-way slab, the limiting deflection is primarily a function of the short span.

  8. Select the correct statement.
    Moment and shear coefficients for continuous beams and slabs can be used when ...


    1. there are minimum 3 spans which differ by not more than 15% of the longest span
    2. there are maximum 3 spans which differ by not more than 15% of the longest span
    3. there are minimum 3 spans which differ by not more than 25% of the longest span
    4. there are maximum 3 spans which differ by not more than 25% of the longest span

    View Answer
    Answer: a
    As per IS 456:2000, Cl 22.5.1, these coefficients can be used only when the numbers of spans are 3 or more which differ by not more than 15% of the longest span.

  9. A continuous RC beam spans 6 span segments, each supporting a monolithic reinforced concrete slab.
    The beam will best be designed ...


    1. as a rectangular one throughout the span
    2. as a T-beam throughout the span
    3. as a rectangular beam for span moments and T-beam for support moments
    4. as a T-beam for span moments and rectangular beam for support moments

    View Answer
    Answer: d
    This question was asked in IES [2002]
    At supports there will be hogging moment i.e., tension will be above NA and compression will be below NA. As concrete is weak in tension, the beam at supports should be designed as a rectangular beam.
    For span moments, the beam is designed as T-beam, as due to monolithic reinforced concrete slab, some part of the slab will act as a flange for the beam at each of 6 span segments.

  10. Shrinkage in a concrete slab ...


    1. causes shear cracks
    2. causes tension cracks
    3. causes compression cracks
    4. does not cause any cracking

    View Answer
    Answer: b
    This question was asked in IES [2002]
    Cracking due to shrinkage occurs due to restraints that cause tensile stresses and strains in concrete.

  11. A flat slab is supported by ...


    1. beams
    2. walls
    3. columns
    4. all of the above

    View Answer
    Answer: c

  12. What is the minimum thickness of a flat slab?


    1. 100 mm
    2. 125 mm
    3. 150 mm
    4. 175 mm

    View Answer
    Answer: b
    As per IS 456:2000, Cl 31.2.1, the minimum thickness is 125 mm.

  13. A thick rectangular portion below the flat slab is called ____.


    1. Column head
    2. Capital
    3. Drop
    4. none of the above

    View Answer
    Answer: c

  14. The width of a column strip in a flat slab is ...


    1. 1/2 of the span
    2. 1/3 of the span
    3. 1/4 of the span
    4. 1/5 of the span

    View Answer
    Answer: c
    As per IS 456:2000, Cl 31.1.1 [a], the width of the column strip is $0.25 {l}_{2}$ but not greater than $0.25 {l}_{1}$. Where, ${l}_{1}$ is the span in the direction moments are being determined and ${l}_{2}$ is the transverse span to ${l}_{1}$





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