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. 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

2. 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

3. 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

4. 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

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

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

6. 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

7. [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

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

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

  • 0.15 %
  • 1.5 %
  • 4 %
  • 1 %

15. 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

16. 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

17. 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

18. 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

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

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

20. 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

21. 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

22. A ribbed slab is provided for

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

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

  • 30
  • 35
  • 40
  • 50

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. 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

26. 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

27. 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

28. 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

29. 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

30. 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

31. 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

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. 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

34. 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

35. 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

36. The minimum clear cover for R.C.C. columns shall be

  • Greater of 40 mm or diameter
  • Smaller of 40 mm or diameter
  • Greater of 25 mm or diameter
  • Smaller of 25 mm or diameter

37. A pre-stressed rectangular beam which carries two concentrated loads W at L/3 from either end, is provided with a bent tendon with tension P such that central one-third portion of the tendon remains parallel to the longitudinal axis, the maximum dip h is

  • WL/P
  • WL/2P
  • WL/3P
  • WL/4P

38. An R.C.C. beam of 6 m span is 30 cm wide and has a lever arm of 55 cm. If it carries a U.D.L. of 12 t per m and allowable shear stress is 5 kg/cm², the beam

  • Is safe in shear
  • Is safe with stirrups
  • Is safe with stirrups and inclined bars
  • Needs revision of section

39. 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

40. 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

41. A foundation is called shallow if its depth, is

  • One-fourth of its width
  • Half of its width
  • Three-fourth of its width
  • Equal to its width

42. If the tendon is placed at an eccentricity e below the centroidal axis of the longitudinal axis of a rectangular beam (sectional modulus Z and stressed load P in tendon) the stress at the extreme top edge

  • Is increased by PZ/e
  • Is increased by Pe/Z
  • Is decreased by Pe/Z
  • Remains unchanged

43. If the length of an intermediate span of a continuous slab is 5 m, the length of the end span is kept

  • 4.5 m
  • 4.0 m
  • 3.5 m
  • 3.0 m

44. 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

45. 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

46. An R.C.C beam of 25 cm width has a clear span of 5 metres and carries a U.D.L. of 2000 kg/m inclusive of its self weight. If the lever arm of the section is 45 cm., the beam is

  • Safe in shear
  • Is safe with stirrups
  • Is safe with stirrups and inclined members
  • Needs revision of the section

47. If the ratio of long and short spans of a two way slab with corners held down is r, the actual reduction of B.M. is given by

  • (5/6) (r/1 + r²) M
  • (5/6) (r²/1 + r²) M
  • (5/6) (r²/1 + r³) M
  • (5/6) (r²/1 + r⁴) M

48. In a pre-stressed beam carrying an external load W with a bent tendon is having angle of inclination ? and pre-stressed load P. The net downward load at the centre is

  • W - 2P cos θ
  • W - P cos θ
  • W - P sin θ
  • W - 2P sin θ

49. Total pressure on the vertical face of a retaining wall of height h acts parallel to free surface and from the base at a distance of

  • h/4
  • h/3
  • h/2
  • 2h/3

50. If L is the effective span of a R.C.C. beam which is subjected to maximum shear qmax at the ends, the distance from either end over which stirrups for the shear, are provided, is

  • (L/2) (1 - 3/qmax)
  • (L/3) (1 - 5/qmax)
  • (L/2) (1 - 5/qmax)
  • (L/2) (1 - 2/qmax)

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