RCC Structures Design MCQ Questions & Answers

41

If $${{l_1}}$$ and $${{l_2}}$$ are the lengths of long and short spans of a two way slab simply supported on four edges and carrying a load w per unit area, the ratio of the loads split into w₁ and w₂ acting on strips parallel to $${{l_2}}$$ and $${{l_1}}$$ is

A) $$\frac{{{{\text{w}}_1}}}{{{{\text{w}}_2}}} = \frac{{{l_2}}}{{{l_1}}}$$ B) $$\frac{{{{\text{w}}_1}}}{{{{\text{w}}_2}}} = {\left( {\frac{{{l_2}}}{{{l_1}}}} \right)^2}$$ C) $$\frac{{{{\text{w}}_1}}}{{{{\text{w}}_2}}} = {\left( {\frac{{{l_2}}}{{{l_1}}}} \right)^3}$$ D) $$\frac{{{{\text{w}}_1}}}{{{{\text{w}}_2}}} = {\left( {\frac{{{l_2}}}{{{l_1}}}} \right)^4}$$

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Answer & Solution

Answer: Option D

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42

The minimum thickness of a flat slab is taken

A) 13 cm B) $$\frac{{\text{L}}}{{32}}$$ for end panels without drops C) $$\frac{{\text{L}}}{{36}}$$ for end panels without drops D) $$\frac{{\text{L}}}{{36}}$$ for interior panels without drop E) All the above

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Answer & Solution

Answer: Option E

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43

Columns may be made of plain concrete if their unsupported lengths do not exceed their least lateral dimension

A) Two times B) Three times C) Four times D) Five times

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Answer & Solution

Answer: Option B

Solution:

In RCC design, plain concrete columns are allowed only when the column is short and not subjected to significant bending.

According to standard design guidelines, a column can be made of plain concrete if its unsupported length does not exceed three times its least lateral dimension.

This limitation ensures that the column behaves primarily under axial compression and avoids buckling or instability.

If the length exceeds this limit, reinforcement becomes necessary to provide additional strength and stability.

Therefore, the correct condition is three times the least lateral dimension.

44

The number of treads in a flight is equal to

A) Risers in the flight B) Risers plus one C) Risers minus one D) None of these

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Answer & Solution

Answer: Option C

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45

An R.C.C. column of 30 cm diameter is reinforced with 6 bars 12 mm φ placed symmetrically along the circumference. If it carries a load of 40,000 kg axially, the stress is

A) 49.9 kg/cm² B) 100 kg/cm² C) 250 kg/cm² D) 175 kg/cm²

Discuss

Answer & Solution

Answer: Option A

Solution:

Given: Diameter of R.C.C. column D = 30 cm; 6 bars of 12 mm (1.2 cm) diameter; Axial load P = 40,000 kg

Gross area of column (A_g): (π/4)D² = (π/4)(30)² = 706.86 cm²

Area of one bar: (π/4)d² = (π/4)(1.2)² = 1.131 cm² (approx.)

Total steel area (A_s): 6 × 1.131 = 6.786 cm²

Net concrete area (A_c): A_g − A_s = 706.86 − 6.786 = 700.07 cm²

Assume modular ratio (m): 15 (typical for RCC working stress method)

Transformed area carrying load: A_c + mA_s = 700.07 + 15×6.786 = 801.86 cm²

Concrete stress (working): σ_c = P / (A_c + mA_s) = 40,000 / 801.86 = 49.9 kg/cm²

Therefore, the stress is 49.9 kg/cm² ⇒ Option A.

46

If d and n are the effective depth and depth of the neutral axis respectively of a singly reinforced beam, the lever arm of the beam, is

A) d B) n C) $${\text{d}} + \frac{{\text{n}}}{3}$$ D) $${\text{d}} - \frac{{\text{n}}}{3}$$

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Answer & Solution

Answer: Option D

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47

The allowable tensile stress in mild steel stirrups, reinforced cement concrete, is

A) 1400 kg/cm² B) 190 kg/cm² C) 260 kg/cm² D) 230 kg/cm²

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Answer & Solution

Answer: Option A

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48

In a singly reinforced beam, the effective depth is measured from its compression edge to

A) Tensile edge B) Tensile reinforcement C) Neutral axis of the beam D) Longitudinal central axis

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Answer & Solution

Answer: Option B

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49

The steel generally used in R.C.C. work, is

A) Stainless B) Mild steel C) High carbon steel D) High tension steel

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Answer & Solution

Answer: Option B

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50

The advantage of reinforced concrete, is due to

A) Monolithic character B) Fire-resisting and durability C) Economy because of less maintenance cost D) All the above

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Answer & Solution

Answer: Option D

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RCC Structures Design MCQ Questions & Answers | Civil Engineering