### Multiple Choice Questions and Answers (MCQs) on RCC Structures Design

01. 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

(A) Is safe in shear
(B) Is safe with stirrups
(C) Is safe with stirrups and inclined bars
(D) Needs revision of section

Answer: Option D

02. 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

(A) Half of the width of the slab
(B) Two-third of the width of the slab
(C) Three-fourth of the width of the slab
(D) Four-fifth of the width of the slab

Answer: Option C

03. The load stress of a section can be reduced by

(A) Decreasing the lever arm
(B) Increasing the total perimeter of bars
(C) Replacing larger bars by greater number of small bars
(D) Replacing smaller bars by greater number of greater bars

Answer: Option C

04. The diameter of the column head support a flat slab, is generally kept

(A) 0.25 times the span length
(B) 0.25 times the diameter of the column
(C) 4.0 cm larger than the diameter of the column
(D) 5.0 cm larger than the diameter of the column

Answer: Option A

05. 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

(A) 3WR²/16
(B) 2WR²/16
(C) WR²/16
(D) None of these

Answer: Option C

06. The maximum ratio of span to depth of a slab simply supported and spanning in one direction, is

(A) 35
(B) 25
(C) 30
(D) 20

Answer: Option C

07. If the width of the foundation for two equal columns is restricted, the shape of the footing generally adopted, is

(A) Square
(B) Rectangular
(C) Trapezoidal
(D) Triangular

Answer: Option B

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

(A) 0.7
(B) 0.8
(C) 0.9
(D) 0.6

Answer: Option C

09. Pick up the correct statement from the following:

(A) Lateral reinforcement in R.C.C. columns is provided to prevent the longitudinal reinforcement from buckling
(B) Lateral reinforcement prevents the shearing of concrete on diagonal plane
(C) Lateral reinforcement stops breaking away of concrete cover, due to buckling
(D) All the above

Answer: Option D

10. In case the factor of safety against sliding is less than 1.5, a portion of slab is constructed downwards at the end of the heel slab, which is known as

(A) A key
(B) A cut-off wall
(C) A rib
(D) All the above

Answer: Option D

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

(A) 18 mm diameter
(B) 24 mm diameter
(C) 30 mm diameter
(D) 36 mm diameter

Answer: Option D

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

(A) One diameter
(B) 2.5 diameters
(C) 3 diameters
(D) 3.5 diameters

Answer: Option A

13. For a ribbed slab

(A) Clear spacing between ribs shall not be greater than 4.5 cm
(B) Width of the rib shall not be less than 7.5 cm
(C) Overall depth of the slab shall not exceed four times the breadth of the rib
(D) All the above

Answer: Option D

14. A very comfortable type of stairs is

(A) Straight
(B) Dog legged
(C) Geometrical
(D) Open newel

Answer: Option D

15. 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

Answer: Option C

16. The width of the flange of a L-beam, should be less than

(A) One-sixth of the effective span
(B) Breadth of the rib + four times thickness of the slab
(C) Breadth of the rib + half clear distance between ribs
(D) Least of the above

Answer: Option D

17. A pre-stressed concrete member is preferred because

(A) Its dimensions are not decided from the diagonal tensile stress
(B) Large size of long beams carrying large shear force need not be adopted
(C) Removal of cracks in the members due to shrinkage
(D) All the above

Answer: Option D

18. If the ratio of the span to the overall depth does not exceed 10, the stiffness of the beam will ordinarily be satisfactory in case of a

(A) Simply supported beam
(B) Continuous beam
(C) Cantilever beam
(D) None of these

Answer: Option C

19. A pile of length ‘L’ carrying a uniformly distributed load ‘W’ per metre length is suspended at two points, the maximum, B.M. at the centre of the pile or at the points of suspension, is

(A) WL/8
(B) WL²/24
(C) WL²/47
(D) WL²/16

Answer: Option C

20. If ‘p’ is the net upward pressure on a square footing of side ‘b’ for a square column of side ‘a’, the maximum bending moment is given by

(A) B.M = pb (c – a)/4
(B) B.M = pb (b – a)²/4
(C) B.M = pb (b – a)²/8
(D) B.M = pb (b + a)/8

Answer: Option C

21. To ensure uniform pressure distribution, the thickness of the foundation, is

(A) Kept uniform throughout
(B) Increased gradually towards the edge
(C) Decreased gradually towards the edge
(D) Kept zero at the edge

Answer: Option C

22. According to load factor method, the permissible load ‘W’ on a short column reinforced with longitudinal bars and lateral stirrups, is

(A) Stress in concrete × area of concrete
(B) Stress in steel × area of steel
(C) Stress in concrete × area of concrete + Stress in steel × area of steel
(D) None of these

Answer: Option C

23. 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:

(A) [(p₁ – p₂)/2] + [(p₁ + p₂)/2] sin 2θ
(B) [(p₁ – p₂)/2] + [(p₁ + p₂)/2] cos 2θ
(C) [(p₁ + p₂)/2] + [(p₁ – p₂)/2] cos 2θ
(D) [(p₁ + p₂)/2] + [(p₁ – p₂)/2] sin 2θ

Answer: Option C

24. The maximum permissible size of aggregates to be used in casting the ribs of a slab, is

(A) 5 mm
(B) 7.5 mm
(C) 10 mm
(D) 15 mm

Answer: Option C

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

(A) Are curtailed if not required to resist the bending moment
(B) Are bent up at suitable places to serve as shear reinforcement
(C) Are bent down at suitable places to serve as shear reinforcement
(D) Are maintained at bottom to provide at least local bond stress

Answer: Option C

26. 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

Answer: Option D

27. The minimum thickness of the cover at the end of a reinforcing bar should not be less than twice the diameter of the bar subject to a minimum of

(A) 10 mm
(B) 15 mm
(C) 20 mm
(D) 25 mm

Answer: Option D

28. Top bars are extended to the projecting parts of the combined footing of two columns Ldistance apart for a distance of

(A) 0.1 L from the outer edge of column
(B) 0.1 L from the centre edge of column
(C) Half the distance of projection
(D) One-fourth the distance of projection

Answer: Option B

29. For M 150 grade concrete (1:2:4) the moment of resistance factor is

(A) 0.87
(B) 8.50
(C) 7.50
(D) 5.80

Answer: Option B

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

(A) f = (P/A) – (Z/M)
(B) f = (A/P) – (M/Z)
(C) f = (P/A) – (M/Z)
(D) f = (P/A) – (M/6Z)

Answer: Option C

31. 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:

(A) (1 – C)mf – eE
(B) (C – 1)mf + eE
(C) (C – 1)mf – eE
(D) (1 – C)mf + eE

Answer: Option B

32. In a pre-stressed member it is advisable to use

(A) Low strength concrete only
(B) High strength concrete only
(C) Low strength concrete but high tensile steel
(D) High strength concrete and high tensile steel

Answer: Option D

33. 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

(A) Triangular load of the wall
(B) UDL of wall
(C) UDL of wall + load from the roof
(D) Triangular load + load from the roof

Answer: Option C

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

(A) Greater of 40 mm or diameter
(B) Smaller of 40 mm or diameter
(C) Greater of 25 mm or diameter
(D) Smaller of 25 mm or diameter

Answer: Option C

35. The minimum thickness of a flat slab is taken

(A) L/32 for end panels without drops
(B) L/36 for end panels without drops
(C) L/36 for interior panels without drop
(D) All the above

Answer: Option D

36. 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

Answer: Option D

37. 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

(A) Safe in shear
(B) Is safe with stirrups
(C) Is safe with stirrups and inclined members
(D) Needs revision of the section

Answer: Option A

38. The neutral axis of a T-beam exists

(A) Within the flange
(B) At the bottom edge of the slab
(C) Below the slab
(D) All the above

Answer: Option D

39. A pre-cast pile generally used, is

(A) Circular
(B) Square
(C) Octagonal
(D) Square with corners chamfered

Answer: Option D

40. 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

Answer: Option D

41. The self-weight of the footing, is

(A) Not considered for calculating the upward pressure on footing
(B) Also considered for calculating the upward pressure on footing
(C) Not considered for calculating the area of the footing
(D) Both (b) and (c)

Answer: Option A

42. Pick up the incorrect statement from the following:

(A) In the stem of a retaining wall, reinforcement is provided near the earth side
(B) In the toe slab of a retaining wall, reinforcement is provided at the bottom of the slab
(C) In the heel slab of a retaining wall, reinforcement is provided at the top of the slab
(D) None of these

Answer: Option D

43. If the bearing capacity of soil is 10 tonnes/cm2 and the projection of plain concrete footing from walls, is a cm, the depth D of footing is

(A) D = 0.0775 a
(B) D = 0.775 a
(C) D = 0.775 √a
(D) D = 0.775 a2

Answer: Option B

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

(A) Shrinkage of concrete
(B) Elastic shortening of concrete
(C) Creep of concrete
(D) All the above

Answer: Option D

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

(A) 1/4th of the span
(B) 1/5th of the span
(C) 1/6th of the span
(D) 1/7th of the span

Answer: Option D

46. 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

(A) R + T
(B) T – R
(C) √(R2 + T2)
(D) R – T

Answer: Option C

47. If p1 and P2 are effective lateral loadings at the bottom and top exerted by a level earth subjected to a super-load on the vertical face of height h of a retaining wall, the horizontal pressure p per unit length of the wall, is

(A) [(p₁ – p₂)/2] h
(B) [(p₁ + p₂)/4] h
(C) [(p₁ + p₂)/2] h
(D) (p₁ – p₂) ⅔h

Answer: Option C

48. In the zone of R.C.C. beam where shear stress is less than 5 kg/cm2, nominal reinforcement is provided at a pitch of

(A) One-half lever arm of the section
(B) One-third lever arm of the section
(C) Lever arm of the section
(D) One and half lever arm of the section

Answer: Option C

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

(A) Distribute the load
(B) Resist the temperature stresses
(C) Resist the shrinkage stress
(D) All the above

Answer: Option D

50. Long and short spans of a two way slab are ly and lx and load on the slab acting on strips parallel to lx and ly be wx and wy respectively. According to Rankine Grashoff theory

(A) (wx/wy) = (ly/lx)
(B) (wx/wy) = (ly/lx)²
(C) (wx/wy) = (ly/lx)4
(D) None of these

Answer: Option C