About RCC Structures Design

Following are some of the multiple choice questions on the RCC Structures Design with answers that will help the students in developing their knowledge.

RCC Structures Design MCQ

1. An R.C.C. roof slab is designed as a two way slab if

  • It supports live loads in both directions
  • The ratio of spans in two directions is less than 2
  • The slab is continuous over two supports
  • The slab is discontinuous at edges

2. The maximum shear stress (q) in concrete of a reinforced cement concrete beam is

  • Shear force/(Lever arm × Width)
  • Lever arm/(Shear force × Width)
  • Width/(Lever arm × Shear force)
  • (Shear force × Width)/Lever arm

3. According to I.S. : 456, slabs which span in two directions with corners held down, are assumed to be divided in each direction into middle strips and edge strips such that the width of the middle strip, is

  • Half of the width of the slab
  • Two-third of the width of the slab
  • Three-fourth of the width of the slab
  • Four-fifth of the width of the slab

4. An R.C.C. column is treated as short column if its slenderness ratio is less than

  • 30
  • 35
  • 40
  • 50

5. The reinforced concrete beam which has width 25 cm, lever arm 40 cm, shear force 6t/cm², safe shear stress 5 kg/cm² and B.M. 24 mt,

  • Is safe in shear
  • Is unsafe in shear
  • Is over safe in shear
  • Needs redesigning

6. Distribution of shear intensity over a rectangular section of a beam, follows:

  • A circular curve
  • A straight line
  • A parabolic curve
  • An elliptical curve

7. An R.C.C. lintel is spanning an opening of 2 m span in a brick wall. The height of the roof is 2.9 m above the floor level and that of the opening is 2.1 m above the floor level. The lintel is to be designed for self weight plus

  • Triangular load of the wall
  • UDL of wall
  • UDL of wall + load from the roof
  • Triangular load + load from the roof

8. If ‘W’ is weight of a retaining wall and ‘P’ is the horizontal earth pressure, the factor of safety against sliding, is

  • 1.0
  • 1.25
  • 1.5
  • 2.0

9. The width of the rib of a T-beam, is generally kept between

  • 1/7 to 1/3 of rib depth
  • 1/3 to 1/2 of rib depth
  • 1/2 to 3/4 of rib depth
  • 1/3 to 2/3 of rib depth

10. The thickness of base slab of a retaining wall generally provided, is

  • One half of the width of the stem at the bottom
  • One-third of the width of the stem at the bottom
  • One fourth of the width of the steam at the bottom
  • Width of the stem at the bottom

11. A T-beam behaves as a rectangular beam of a width equal to its flange if its neutral axis

  • Remains within the flange
  • Remains below the slab
  • Coincides the geometrical centre of the beam
  • None of these

12. If the sides of a slab simply supported on edges and spanning in two directions are equal, the maximum bending moment is multiplied by

  • 0.2
  • 0.3
  • 0.4
  • 0.5

13. In a simply supported slab, alternate bars are curtailed at

  • 1/4th of the span
  • 1/5th of the span
  • 1/6th of the span
  • 1/7th of the span

14. A part of the slab may be considered as the flange of the T-beam if

  • Flange has adequate reinforcement transverse to beam
  • It is built integrally with the beam
  • It is effectively bonded together with the beam
  • All the above

15. The advantage of a concrete pile over a timber pile, is

  • No decay due to termites
  • No restriction on length
  • Higher bearing capacity
  • All the above

16. The maximum diameter of a bar used in a ribbed slab, is

  • 12 mm
  • 6 mm
  • 20 mm
  • 22 mm

17. [A + (m - 1)ASC] known as equivalent concrete area of R.C.C. is given by

  • Modular ratio method
  • Load factor method
  • Ultimate load method
  • None of these

18. If the size of a column is reduced above the floor, the main bars of the columns, are

  • Continued up
  • Bent inward at the floor level
  • Stopped just below the floor level and separate lap bars provided
  • All the above

19. After pre-stressing process is completed, a loss of stress is due to

  • Shrinkage of concrete
  • Elastic shortening of concrete
  • Creep of concrete
  • All the above

20. The maximum area of tension reinforcement in beams shall not exceed

  • 0.15 %
  • 1.5 %
  • 4 %
  • 1 %

21. According to the steel beam theory of doubly reinforced beams

  • Tension is resisted by tension steel
  • Compression is resisted by compression steel
  • Stress in tension steel equals the stress in compression steel
  • All the above

22. If the maximum dip of a parabolic tendon carrying tension P is h and the effective length of the pre-stressed beam is L, the upward uniform pressure will be

  • 8hp/l
  • 8hp/l²
  • 8hl/p
  • 8hl/p²

23. If R and T are rise and tread of a stair spanning horizontally, the steps are supported by a wall on one side and by a stringer beam on the other side, the steps are designed as beams of width

  • R + T
  • T - R
  • √(R² + T²)
  • R - T

24. The floor slab of a building is supported on reinforced cement floor beams. The ratio of the end and intermediate spans is kept

  • 0.7
  • 0.8
  • 0.9
  • 0.6

25. A ribbed slab is provided for

  • A plain ceiling
  • Thermal insulation
  • Acoustic insulation
  • All the above

26. The thickness of the topping of a ribbed slab, varies between

  • 3 cm to 5 cm
  • 5 cm to 8 cm
  • 8 cm to 10 cm
  • 12 cm to 15 cm

27. The diameter of transverse reinforcement of columns should be equal to one-fourth of the diameter of the main steel rods but not less than

  • 4 mm
  • 5 mm
  • 6 mm
  • 7 mm

28. If C is creep coefficient, f is original pre-stress in concrete, m is modular ratio, E is Young's modulus of steel and e is shrinkage strain, the combined effect of creep and shrinkage is:

  • (1 - C) mf - eE
  • (C - 1) mf + eE
  • (C - 1) mf - eE
  • (1 - C) mf + eE

29. The percentage of minimum reinforcement of the gross sectional area in slabs, is

  • 0.10 %
  • 0.12 %
  • 0.15 %
  • 0.18 %

30. If ‘W’ is the uniformly distributed load on a circular slab of radius ‘R’ fixed at its ends, the maximum positive radial moment at its centre, is

  • 3WR²/16
  • 2WR²/16
  • WR²/16
  • None of these

31. The stem of a cantilever retaining wall which retains earth level with top is 6 m. If the angle of repose and weight of the soil per cubic metre are 30° and 2000 kg respectively, the effective width of the stem at the bottom, is

  • 51.5
  • 52.5
  • 53.5
  • 54.5

32. If ‘H’ is the overall height of a retaining wall retaining a surcharge, the width of the base slab usually provided, is

  • 0.3 H
  • 0.4 H
  • 0.5 H
  • 0.7 H

33. If p₁ and p₂ are mutually perpendicular principal stresses acting on a soil mass, the normal stress on any plane inclined at angle θ° to the principal plane carrying the principal stress p₁, is:

  • [(p₁ - p₂)/2] + [(p₁ + p₂)/2] sin 2θ
  • [(p₁ - p₂)/2] + [(p₁ + p₂)/2] cos 2θ
  • [(p₁ + p₂)/2] + [(p₁ - p₂)/2] cos 2θ
  • [(p₁ + p₂)/2] + [(p₁ - p₂)/2] sin 2θ

34. Bottom bars under the columns are extended into the interior of the footing slab to a distance greater than

  • 42 diameters from the centre of the column
  • 42 diameters from the inner edge of the column
  • 42 diameters from the outer edge of the column
  • 24 diameters from the centre of the column

35. The transverse reinforcements provided at right angles to the main reinforcement

  • Distribute the load
  • Resist the temperature stresses
  • Resist the shrinkage stress
  • All the above

36. The amount of reinforcement for main bars in a slab, is based upon

  • Minimum bending moment
  • Maximum bending moment
  • Maximum shear force
  • Minimum shear force

37. For initial estimate for a beam design, the width is assumed

  • 1/15th of span
  • 1/20th of span
  • 1/25th of span
  • 1/30th of span

38. Lapped splices in tensile reinforcement are generally not used for bars of size larger than

  • 18 mm diameter
  • 24 mm diameter
  • 30 mm diameter
  • 36 mm diameter

39. If a rectangular pre-stressed beam of an effective span of 5 meters and carrying a total load 3840 kg/m, is designed by the load balancing method, the central dip of the parabolic tendon should be

  • 5 cm
  • 10 cm
  • 15 cm
  • 20 cm

40. An R.C.C. beam of 25 cm width and 50 cm effective depth has a clear span of 6 meters and carries a U.D.L. of 3000 kg/m inclusive of its self weight. If the lever arm constant for the section is 0.865, the maximum intensity of shear stress, is

  • 8.3 kg/cm²
  • 7.6 kg/cm²
  • 21.5 kg/cm²
  • 11.4 kg/cm²

41. The width of the flange of a T-beam, which may be considered to act effectively with the rib depends upon

  • Breadth of the rib
  • Overall thickness of the rib
  • Centre to centre distance between T-beams
  • All the above

42. Pick up the incorrect statement from the following: Tensile reinforcement bars of a rectangular beam

  • Are curtailed if not required to resist the bending moment
  • Are bent up at suitable places to serve as shear reinforcement
  • Are bent down at suitable places to serve as shear reinforcement
  • Are maintained at bottom to provide at least local bond stress

43. The radius of a bar bend to form a hook, should not be less than

  • Twice the diameter
  • Thrice the diameter
  • Four times the diameter
  • Five times the diameter

44. If T and R are tread and rise respectively of a stair, then

  • 2R + T = 60
  • R + 2T = 60
  • 2R + T = 30
  • R + 2T= 30

45. If A is the area of the foundation of a retaining wall carrying a load W and retaining earth of weight 'w' per unit volume, the minimum depth (h) of the foundation from the free surface of the earth, is

  • h = (W/Aw) [(1 - sin φ)/(1 + sin φ)]
  • h = (W/Aw) [(1 + sin φ)/(1 + sin φ)]
  • h = (W/Aw) [(1 - sin φ)/(1 + sin φ)]²
  • h = √(W/Aw) [(1 - sin φ)/(1 + sin φ)]²

46. An intermediate T-beam reinforced with two layers of tensile steel with clear cover 13 cm encased with the floor of a hall 12 meters by 7 meters, is spaced at 3 meters from adjoining beams and if the width of the beam is 20 cm, the breadth of the flange is

  • 300 cm
  • 233 cm
  • 176 cm
  • 236 cm

47. Minimum spacing between horizontal parallel reinforcement of the same size should not be less than

  • One diameter
  • 2.5 diameters
  • 3 diameters
  • 3.5 diameters

48. Minimum spacing between horizontal parallel reinforcement of different sizes, should not be less than

  • One diameter of thinner bar
  • One diameter of thicker bar
  • Twice the diameter of thinner bar
  • None of these

49. If W is total load per unit area on a panel, D is the diameter of the column head, L is the span in two directions, then the sum of the maximum positive bending moment and average of the negative bending moment for the design of the span of a square flat slab, should not be less than

  • WL/12 (L - 2D/3)²
  • WL/10 (L + 2D/3)²
  • WL/10 (L - 2D/3)²
  • WL/12 (L - D/3)²

50. The diameter of main bars in R.C.C. columns, shall not be less than

  • 6 mm
  • 8 mm
  • 10 mm
  • 12 mm

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