RCC Structures Design Questions and Answers Section-2

RCC – Structures Design

QUESTION –  51

The pitch of the main bars in a simply supported slab, should not exceed its effective depth by

A. Three times

B. Four times

C. Five times

D. Six times

ANS: D

QUESTION –  52

High strength concrete is used in pre-stressed member

A. To overcome high bearing stresses developed at the ends

B. To overcome bursting stresses at the ends

C. To provide high bond stresses

D. All the above

ANS: D

QUESTION –  53
on a circular slab of radius , the maximum radial moment at the centre of the
If is the load
slab, is WR²/16
A.
B. 2WR²/16
C. 3WR²/16
D. 5WR²/16
ANS: C

QUESTION –  54

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 )/(1 + sin )]
A. h = (W/Aw) [(1 –
B. h = (W/Aw) [(1 + )/(1 + sin )]
C. h = (W/Aw) [(1 – )/(1 + sin )]²
D. h W/Aw) [(1 – )/(1 + sin )]²
ANS: C

QUESTION –  55

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 At of the steel required for an economic section, is

A. 0.496 %

B. 0.596 %

C. 0.696 %

D. 0.796 %

ANS: C

QUESTION –  56

The modular ratio m of a concrete whose permissible compressive stress is C, may be obtained from the equation.

A. m = 700/3C

B. m = 1400/3C

C. m = 2800/3C

D. m = 3500/3C

ANS: C

RCC Structures Design Questions and Answers

QUESTION –  57

Enlarged head of a supporting column of a flat slab is technically known as

A. Supporting end of the column

B. Top of the column

C. Capital

D. Drop panel ANS: C

QUESTION –  58

Thickened part of a flat slab over its supporting column, is technically known as

A. Drop panel

C. Column head

D. None of these

ANS: A

QUESTION –  59

If is the sectional area of a pre-stressed rectangular beam provided with a tendon pre -stressed
by a force through its centroidal longitudinal axis, the compressive stress in concrete, is
A. P/A
B. A/P
C. P/2A
D. 2A/P
ANS: A

QUESTION –  60

Side face reinforcement shall be provided in the beam when depth of the web in a beam exceeds

A. 50 cm

B. 75 cm

C. 100 cm

D. 120 cm

ANS: B

QUESTION –  61

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

A. WL/P

B. WL/2P

C. WL/3P

D. WL/4P

ANS: C

QUESTION –  62

The minimum head room over a stair must be

A. 200 cm

B. 205 cm

C. 210 cm

D. 230 cm

ANS: C

QUESTION –  63

If q is the punching shear resistance per unit area a, is the side of a square footing for a column of side b, carrying a weight W including the weight of the footing, the depth D. of the footing from punching shear consideration, is

A. D = W (a – b)/4a²bq

B. D = W (a² – b²)/4a²bq

C. D = W (a² – b²)/8a²bq

D. D = W (a² – b²)/4abq

ANS: B

QUESTION –  64

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

A. 1/15th of span

B. 1/20th of span

C. 1/25th of span

D. 1/30th of span

ANS: D

QUESTION –  65

In a slab, the pitch of the main reinforcement should not exceed its effective depth

A. Three times

B. Four times

C. Five times

D. Two times

ANS:

QUESTION –  66
If the length of a combined footing for two columns l metres apart is L and the projection on the
left side of the exterior column is x, then the projection y on the right side of the exterior column,
in order to have a uniformly distributed load, is (where is the distance of centre of gravity of
column loads) .
A. y = L – (l – ) )
B. y = L/2 + (l –
C. y = L/2 – (l + )
D. y = L/2 – (l – )

ANS: D

QUESTION –  67

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

A. h /4

B. h/3

C. h/2

D. 2h/3

ANS: B

QUESTION –  68

If the tendon is placed at an rectangular beam (sectional top edge

A. Is increased by PZ/e

B. Is increased by Pe/Z

C. Is decreased by Pe/Z

D. Remains unchanged ANS: C

eccentricity e below the centroidal axis of the longitudinal axis of a modulus Z and stressed load P in tendon) the stress at the extreme

QUESTION –  69

The Young’s modulus of elasticity of steel, is

A. 150 KN/mm2

B. 200 KN/mm2

C. 250 KN/mm2

D. 275 KN/mm2

ANS: D

QUESTION –  70

Design of a two way slab simply supported on edges and having no provision to prevent the corners from lifting, is made by

A. Rankine formula

B. Marcus formula

C. Rankine Grashoff formula

D. Grashoff formula

ANS: C

QUESTION –  71

Spacing of stirrups in a rectangular beam, is

A. Kept constant throughout the length

B. Decreased towards the centre of the beam

C. Increased at the ends

D. Increased at the centre of the beam

ANS: D

QUESTION –  72

As per IS : 456, the reinforcement in a column should not be less than

A. 0.5% and not more than 5% of cross-sectional area

B. 0.6% and not more than 6% of cross-sectional area

C. 0.7% and not more than 7% of cross-sectional area

D. 0.8% and not more than 8% of cross-sectional area ANS: D
QUESTION –  73

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 ANS: A

QUESTION –  74

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

A. 42 diameters from the centre of the column

B. 42 diameters from the inner edge of the column

C. 42 diameters from the outer edge of the column

D. 24 diameters from the centre of the column

ANS: C

QUESTION –  75

Pick up the assumption for the design of a pre-stressed concrete member from the following:

A. A transverse plane section remains a plane after bending

B. During deformation limits, Hook’s law is equally applicable to concrete as well as to steel

C. Variation of stress in reinforcement due to changes in external loading is negligible

D. All the above

ANS: D


QUESTION –  76

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

ANS: D

QUESTION –  77

RCC Structures Design Questions and Answers

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

A. 30

B. 35

C. 40

D. 50

ANS: D

QUESTION –  78

The zone in which transverse bending is likely to occur may be obtained by drawing a line from the

A. 30°

B. 45°

C. 60°

D. None of these ANS: B

QUESTION –  79

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

A. 3 cm to 5 cm

B. 5 cm to 8 cm

C. 8 cm to 10 cm

D. 12 cm to 15 cm

ANS: B

QUESTION –  80

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

A. 4.5 m

B. 4.0 m

C. 3.5 m

D. 3.0 m

ANS: A

QUESTION –  81

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

A. (L/2) (1 – 3/qmax)

B. (L/3) (1 – 5/qmax)

C. (L/2) (1 – 5/qmax)

D. (L/2) (1 – 2/q )

ANS: Cmax

QUESTION –  82

The angle of internal friction of soil mass is the angle whose

A. Tangent is equal to the rate of the maximum resistance to sliding on any internal inclined plane to the normal pressure acting on the plane

B. Sine is equal to the ratio of the maximum resistance to sliding on any internal inclined plane to the normal pressure acting on the plane

C. Cosine is equal to the ratio of the maximum resistance sliding on any internal inclined plane to the normal pressure acting on the plane

D. None of these

ANS: A

QUESTION –  83

The maximum ratio of span to depth of a slab simply supported and spanning in two directions, is

A. 25

B. 30

C. 35

D. 40

ANS: C

QUESTION –  84

If T and R are the tread and rise of a stair which carries a load w per square metre on slope, the corresponding load per square metre of the horizontal area, is

A. w (R + T)/T

B. w (R² + T²)/T

C. w (R + T)/T

D. w (R/T)

ANS: B

QUESTION –  85

If the loading on a pre-stressed rectangular beam, is uniformly distributed, the tendon to be provided should be.

A. Straight below centroidal axis

B. Parabolic with convexity downward

C. Parabolic with convexity upward

D. Straight above centroidal axis

ANS: B

QUESTION –  86

For normal cases, stiffness of a simply supported beam is satisfied if the ratio of its span to its overall depth does not exceed

A. 10

B. 15

C. 20

D. 25

ANS: C

QUESTION –  87

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

A. 8hp/ l

B. 8hp/l²

C. 8hl/p

D. 8hl/p²

ANS: B

QUESTION –  88

If depth of slab is 10 cm, width of web 30 cm, depth of web 50 cm, centre to centre distance of beams 3 m, effective span of beams 6 m, the effective flange width of the beam, is

A. 200 cm

B. 300 cm

C. 150 cm

D. 100 cm

ANS: C

QUESTION –  89

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

A. Stainless

B. Mild steel

C. High carbon steel

D. High tension steel

ANS: B

QUESTION –  90

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

A. (5/6) (r/1 + r²) M

B. (5/6) (r²/1 + r²) M

C. (5/6) (r²/1 + r3) M

D. (5/6) (r²/1 + r4) M

ANS: D

QUESTION –  91

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

A. Flange has adequate reinforcement transverse to beam

B. It is built integrally with the beam

C. It is effectively bonded together with the beam

D. All the above

ANS: D

QUESTION –  92

By over-reinforcing a beam, the moment of resistance can be increased not more than

A. 10 %

B. 15 %

C. 20 %

D. 25 %

ANS: D

QUESTION –  93 per unit run exerted by the
Total pressure on the vertical face of a retaining wall of height
retained earth weighing per unit volume, is
A. wh [(1 – )/(1 + sin )]
B. wh² [(1 – )/(1 + sin )]
C. wh² [(1 – )/2(1 + sin )]
D. wh² [(1 – )/3(1 + sin )]
ANS: C

QUESTION –  94

A singly reinforced beam has breadth b, effective depth d, depth of neutral axis n and critical neutral axis n1. If fc and ft are permissible compressive and tensile stresses, the moment to resistance of the beam, is

A. bn (fc/2) (d – n/3)

B. Atft (d – n/3)

C. ½ n1 (1 – n1/3) cbd²

D. All the above

ANS: D

QUESTION –  95

According to I.S.: 456, 1978 the thickness of reinforced concrete footing on piles at its edges, is kept less than

A. 5 cm

B. 10 cm

C. 15 cm

D. 20 cm

ANS: C

QUESTION –  96

If l1 and l2 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 w2acting on strips parallel to l2 and l1 is

A. w1/w2 = l2/ l1

B. w1/w2 = (l2/l1)²

C. w1/w2 = (l2/l1)3
D. w /w = (l /l )4
ANS:1 Option22 1D

QUESTION –  97

The live load to be considered for an accessible roof, is

A. Nil

B. 75 kg/m3

C. 150 kg/m 2

D. 200 kg/cm 2

ANS: C

QUESTION –  98

If Ac, Asc and A are areas of concrete, longitudinal steel and section of a R.C.C. column and m and
c are the modular ratio and maximum stress in the configuration of concrete, the
strength of
column is
A. cAc + m cAsc
B. c(A – Asc) + m cAsc
C. c[A + (m – 1)ASC]

D. All the above

ANS: D

QUESTION –  99

On an absolutely rigid foundation base, the pressure will

A. Be more at the edges of the foundation

B. Be uniform

C. Not be uniform

D. Be zero at the centre of the foundation

ANS: C

QUESTION –  100

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

A. 4 mm

B. 5 mm

C. 6 mm

D. 7 mm

ANS: D

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