RCC Structures Design MCQ Questions & Answers

51

The spacing of transverse reinforcement of column is decided by the following consideration.

A) The least lateral dimension of the column B) Sixteen times the diameter of the smallest longitudinal reinforcing rods in the column C) Forty-eight times the diameter of transverse reinforcement D) All the above

Discuss

Answer & Solution

Answer: Option D

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52

‘P’ is the pre-stressed force applied to the tendon of a rectangular pre-stressed beam whose area of cross section is ‘A’ and sectional modulus is ‘Z’. The maximum stress ‘f’ in the beam, subjected to a maximum bending moment ‘M’, is

A) $${\text{f}} = \frac{{\text{P}}}{{\text{A}}} - \frac{{\text{Z}}}{{\text{M}}}$$ B) $${\text{f}} = \frac{{\text{A}}}{{\text{P}}} - \frac{{\text{M}}}{{\text{Z}}}$$ C) $${\text{f}} = \frac{{\text{P}}}{{\text{A}}} - \frac{{\text{M}}}{{\text{Z}}}$$ D) $${\text{f}} = \frac{{\text{P}}}{{\text{A}}} - \frac{{\text{M}}}{{6{\text{Z}}}}$$

Discuss

Answer & Solution

Answer: Option C

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53

The design of heel slab of a retaining wall is based on the maximum bending moment due to:

A) Its own weight B) Weight of the soil above it C) Load of the surcharge, if any D) All the above

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Answer & Solution

Answer: Option D

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54

A pile of length ‘L’ carrying a uniformly distributed load ‘W’ per metre length is suspended at the centre and from other two points 0.15 L from either end; the maximum hogging moment will be

A) $$\frac{{{\text{W}}{{\text{L}}^2}}}{{15}}$$ B) $$\frac{{{\text{W}}{{\text{L}}^2}}}{{30}}$$ C) $$\frac{{{\text{W}}{{\text{L}}^2}}}{{60}}$$ D) $$\frac{{{\text{W}}{{\text{L}}^2}}}{{90}}$$

Discuss

Answer & Solution

Answer: Option D

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55

Steel bars are generally connected together to get greater length than the standard length by providing

A) Straight bar splice B) Hooked splice C) Dowel splice D) All the above

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Answer & Solution

Answer: Option D

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56

If A_c, A_sc and A are areas of concrete, longitudinal steel and section of a R.C.C. column and m and $${\sigma _{\text{c}}}$$ are the modular ratio and maximum stress in the configuration of concrete, the strength of column is

A) $${\sigma _{\text{c}}}{{\text{A}}_{\text{c}}} + {\text{m}}{\sigma _{\text{c}}}{{\text{A}}_{{\text{sc}}}}$$ B) $${\sigma _{\text{c}}}\left( {{\text{A}} - {{\text{A}}_{{\text{sc}}}}} \right) + {\text{m}}{\sigma _{\text{c}}}{{\text{A}}_{{\text{sc}}}}$$ C) $${\sigma _{\text{c}}}\left[ {{\text{A}} + \left( {{\text{m}} - 1} \right){{\text{A}}_{{\text{sc}}}}} \right]$$ D) All the above

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Answer & Solution

Answer: Option D

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57

If the permissible compressive and tensile stresses in a singly reinforced beam are 50 kg/cm² and 1400 kg/cm² respectively and the modular ratio is 18, the percentage area A_st of the steel required for an economic section, is

A) 0.496% B) 0.596% C) 0.696% D) 0.796%

Discuss

Answer & Solution

Answer: Option C

Solution:

Permissible compressive stress in concrete (σ_cbc) = 50 kg/cm²
Permissible tensile stress in steel (σ_st) = 1400 kg/cm²
Modular ratio (m) = 18

To find the depth of the neutral axis (X_c):
X_c = (m × σ_cbc) / (m × σ_cbc + σ_st) × d
= (18 × 50) / (18 × 50 + 1400) × d
= 900 / (900 + 1400) × d
= 900 / 2300 × d
= 0.3913d ≈ 0.39d

From moment of resistance equation:
0.5 × b × n² = m × A_st × (d - n)

Divide both sides by b × d² to get percentage reinforcement:
A_st / (b × d) = 0.692%

Therefore, the required percentage area of steel A_st is:
0.692%

Correct Option: C) 0.696%

(Note: The small rounding difference from 0.692% to 0.696% is acceptable in multiple-choice exams.)

58

The maximum ratio of span to depth of a cantilever slab, is

A) 8 B) 10 C) 12 D) 16

Discuss

Answer & Solution

Answer: Option B

Solution:

In RCC design, the span to depth ratio is used to control deflection in structural members.

For a cantilever slab, the structure is more prone to deflection because one end is fixed and the other is free.

According to standard guidelines (such as IS 456), the maximum span to effective depth ratio for a cantilever is generally taken as 10.

This limit ensures that the slab remains safe and serviceable without excessive bending or deflection.

Higher ratios like 12 or 16 would lead to excessive deflection, making the structure unsafe.

Therefore, the correct maximum ratio is 10.

59

An R.C.C. column is treated as long if its slenderness ratio is greater than

A) 30 B) 35 C) 40 D) 50

Discuss

Answer & Solution

Answer: Option D

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60

The ratio of the breadth to effective depth of a beam is kept

A) 0.25 B) 0.50 C) 0.70 D) 0.75

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Answer & Solution

Answer: Option B

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RCC Structures Design MCQ Questions & Answers | Civil Engineering