RCC Structures Design Questions and Answers Section-4

RCC – Structures Design

QUESTION –  151
The system in which high tensile alloy steel bars (silica manganese steel) are used as prestressing
tendons, is known as
A. Freyssinet system
B. Magnel-Blaton system
C. C.C.L. standard system
D. Lee-McCall system
ANS: D
QUESTION –  152
An under-reinforced section means
A. Steel is provided at the underside only
B. Steel provided is insufficient
C. Steel provided on one face only
D. Steel will yield first
ANS: D
QUESTION –  153
The angle of repose of a soil is the maximum angle which the outer face of the soil mass makes
A. With the horizontal
B. With the vertical
C. With the perpendicular to the inclined plane of the soil
D. None of these
ANS: A


QUESTION –  154

Is In a doubly-reinforced beam if and
the effective depth and is depth of critical neutral axis, the following relationship holds good
A. mc/t = n/(d – n)
B. (m + c)/t = n/(d + n)
C. (t + c)/n = (d + n)/n

D. mc/t = (d – n)/t ANS: A

QUESTION –  155

A raft foundation is provided if its area exceeds the plan area of the building by

A. 10 %

B. 20 %

C. 40 %

D. 50 %

ANS: D

QUESTION –  156

In favourable circumstances a 15 cm concrete cube after 28 days, attains a maximum crushing strength

A. 100 kg/cm2

B. 200 kg/cm2

C. 300 kg/cm2

D. 400 kg/cm2

ANS: D

QUESTION –  157
intensity of pressure at a depth h on a block of earth weighing w per unit
If p1 is the vertical
A. wh (1 – cos )/(1 + ) p2 is

B. wh (1 – sin )/(1 + ) )
C. wh (1 – tan )/(1 +
D. w (1 – cos )/h (1 + sin )
ANS: B

QUESTION –  158

Pick up the incorrect statement from the following. The intensity of horizontal shear stress at the elemental part of a beam section, is directly proportional to

A. Shear force

B. Area of the section

C. Distance of the C.G. of the area from its neutral axis

D. Moment of the beam section about its neutral axis ANS: D

QUESTION –  159

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

A. 20 cm

B. 30 cm

C. 40 cm

D. 75 cm

ANS: B

QUESTION –  160

An R.C.C. beam of 25 cm width and 50 cm effective depth has a clear span of 6 metres 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

A. 8.3 kg/cm2

B. 7.6 kg/cm2

C. 21.5 kg/cm 2

D. 11.4 kg/cm2

ANS: A

QUESTION –  161

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

A. 0.10 %

B. 0.12 %

C. 0.15 %

D. 0.18 %

ANS: C

QUESTION –  162

If the permissible compressive stress for a concrete in bending is C kg/m2, the modular ratio is

A. 2800/C

B. 2300/2C

C. 2800/3C

D. 2800/C2

ANS: C

QUESTION –  163

An R.C.C. beam not provided with shear reinforcement may develop cracks in its bottom inclined roughly to the horizontal at

A. 25°

B. 35°

C. 45°

D. 55°

ANS: C

QUESTION –  164

Cantilever retaining walls can safely be used for a height not more than

A. 3 m

B. 4 m

C. 5 m

D. 6 m

ANS: D

QUESTION –  165

The maximum area of tension reinforcement in beams shall not exceed

A. 0.15 %

B. 1.5 %

C. 4 %

D. 1 %

ANS: C

QUESTION –  166

The width of the flange of a T-beam should be less than

A. One- third of the effective span of the T -beam

B. Distance between the centres of T-beam

C. Breadth of the rib plus twelve times the thickness of the slab

D. Least of the above

ANS: D

QUESTION –  167

For a circular slab carrying a uniformly distributed load, the ratio of the maximum negative to maximum positive radial moment, is

A. 1

B. 2

C. 3

D. 5

ANS: B

QUESTION –  168

According to I.S. : 456 specifications, the safe diagonal tensile stress for M 150 grade concrete, is

A. 5 kg/cm2

B. 10 kg/cm 2

C. 15 kg/cm2

D. 20 kg/cm2

ANS: A

RCC Structures Design Questions and Answers

QUESTION –  169

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

A. Breadth of the rib

B. Overall thickness of the rib

C. Centre to centre distance between T-beams

D. All the above

ANS: D

QUESTION –  170

The maximum shear stress (qmax) in a rectangular beam is

A. 1.25 times the average

B. 1.50 times the average

C. 1.75 times the average

D. 2.0 times the average ANS: B

QUESTION –  171

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

A. 0.2

B. 0.3

C. 0.4

D. 0.5

ANS: D

QUESTION –  172

If K is a constant depending upon the ratio of the width of the slab to its effective span l, x is the distance of the concentrated load from the nearer support, bw is the width of the area of contact of the concentrated load measured parallel to the supported edge, the effective width of the slab be is
A. K/x (1 + x/d) + bw

B. Kx (1 – x/l) + bw

C. Kx (1 + x/l) + bw

D. All the above

ANS: B

QUESTION –  173

The length of the straight portion of a bar beyond the end of the hook, should be at least

A. Twice the diameter

B. Thrice the diameter

C. Four times the diameter

D. Seven times the diameter

ANS: D

QUESTION –  174
bending moment of a simply supported slab is M Kg.cm, the effective depth of the
If the maximum
slab is (where Q is M.R. factor)
A. M/100Q
B. M/ Q
C. M/Q)
D. (M/100Q)
ANS: D
QUESTION –  175
If is the overall height of a retaining wall retaining a surcharge, the width of the base slab

usually provided, is

A. 0.3 H

B. 0.4 H

C. 0.5 H

D. 0.7 H ANS: D

QUESTION –  176
If Sb, is the average bond stress on a bar of diameter subjected to maximum stress , the
length of the embedment is given by
A. l = dt/Sb
B. l = dt/2Sb
C. l = dt/3Sb

D. l = dt/4Sb

ANS: D

QUESTION –  177

If diameter of a reinforcement bar is d, the anchorage value of the hook is

A. 4d

B. 8d

C. 12d

D. 16d

ANS: D

QUESTION –  178

As per I.S. 456 – 1978, the pH value of water shall be

A. Less than 6

B. Equal to 6

C. Not less than 6

D. Equal to 7

ANS: C

QUESTION –  179

For M 150 mix concrete, according to I.S. specifications, local bond stress, is

A. 5 kg/cm2

B. 10 kg/cm 2

C. 15 kg/cm2

D. 20 kg/cm2

ANS: B

QUESTION –  180

The minimum cube strength of concrete used for a pre-stressed member, is

A. 50 kg/cm2

B. 150 kg/cm 2

C. 250 kg/cm2

D. 350 kg/cm2

ANS: D

QUESTION –  181
effective depth and depth of the neutral axis respectively of a singly reinforced
If d and n are the
beam, the lever arm of the beam, is
A. d
B. n
C. d + n/3
D. d – n/3
ANS: D
QUESTION –  182
foundation is assumed as
The weight of a
A. 5% of wall weight
B. 7% of wall weight
C. 10% of wall weight
D. 12% of wall weight
ANS: C
QUESTION –  183
of 30 cm diameter is reinforced with 6 bars 12 mm placed symmetrically along
An R.C.C. column
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
ANS: A
QUESTION –  184

If the diameter of longitudinal bars of a square column is 16 mm, the diameter of lateral ties should not be less than

A. 4 mm

B. 5 mm

C. 6 mm

D. 8 mm

ANS: B

QUESTION –  185

Design of R.C.C. cantilever beams, is based on the resultant force at

A. Fixed end

B. Free end

C. Mid span

D. Mid span and fixed support

ANS: A

QUESTION –  186

In a combined footing if shear stress does not exceed 5 kg/cm2, the nominal stirrups provided are

A. 6 legged

B. 8 legged

C. 10 legged

D. 12 legged

ANS: B

QUESTION –  187

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

A. Shear force/(Lever arm × Width)

B. Lever arm/(Shear force × Width)

C. Width/(Lever arm × Shear force)

D. (Shear force × Width)/Lever arm

ANS: A

QUESTION –  188

An R.C.C. column is treated as long if its slenderness ratio is greater than

A. 30

B. 35

C. 40

D. 50

ANS: D

QUESTION –  189

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

A. One half of the width of the stem at the bottom

B. One -third of the width of the stem at the bottom

C. One fourth of the width of the steam at the bottom

D. Width of the stem at the bottom

ANS: D

QUESTION –  190

Design of R.C.C. simply supported beams carrying U.D.L. is based on the resultant B.M. at

A. Supports

B. Mid span

C. Every section

D. Quarter span

ANS: B

QUESTION –  191

If the maximum shear stress at the end of a simply supported R.C.C. beam of 6 m effective span is 10 kg/cm2, the share stirrups are provided for a distance from either end where, is

A. 50 cm

B. 100 cm

C. 150 cm

D. 200 cm ANS: C

QUESTION –  192

Distribution reinforcement in a simply supported slab, is provided to distribute

A. Load

B. Temperature stress

C. Shrinkage stress

D. All the above

ANS: D

QUESTION –  193

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

A. A circular curve

B. A straight line

C. A parabolic curve

D. An elliptical curve

ANS: C

QUESTION –  194

In a singly reinforced beam, if the permissible stress in concrete reaches earlier than that in steel, the beam section is called

A. Under-reinforced section

B. Over reinforced section

C. Economic section

D. Critical section

ANS: B

QUESTION –  195

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

A. Continued up

B. Bent inward at the floor level

C. Stopped just below the floor level and separate lap bars provided

D. All the above

ANS: D

QUESTION –  196

The minimum number of main steel bars provided in R.C.C.

A. Rectangular columns is 4

B. Circular columns is 6

C. Octagonal columns is 8

D. All the above

ANS: D

QUESTION –  197

A short column 20 cm × 20 cm in section is reinforced with 4 bars whose area of cross section is 20 sq. cm. If permissible compressive stresses in concrete and steel are 40 kg/cm2 and 300 kg/cm2, the Safe load on the column, should not exceed

A. 4120 kg

B. 41,200 kg

C. 412,000 kg

D. None of these

ANS: B

QUESTION –  198

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

A. 2R + T = 60

B. R + 2 T = 60

C. 2R + T = 30

D. R + 2 T = 30

ANS: A

QUESTION –  199

For stairs spanning l metres longitudinally between supports at the bottom and top of a flight carrying a load w per unit horizontal area, the maximum bending moment per metre width, is

A. wl²/4

B. wl²/8

C. wl²/12

D. wl²/16

ANS: D

QUESTION –  200

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

ANS: B

QUESTION –  201

Though the effective depth of a T-beam is the distance between the top compression edge to the centre of the tensile reinforcement, for heavy loads, it is taken as

A. 1/8th of the span

B. 1/10th of the span

C. 1/12th of the span

D. 1/16th of the span

ANS: C

QUESTION –  202

If jd stress at the section having Q shear force, is

A. Q/2

B. Q/3

C. Q/

D. 2 × Q/

ANS: C

QUESTION –  203

On piles, the drop must be at least

A. 80 cm

B. 100 cm

C. 120 cm

D. 140 cm

ANS: C

QUESTION –  204

Steel beam theory is used for

A. Design of simple steel beams

B. Steel beams encased in concrete

C. Doubly reinforced beams ignoring compressive stress in concrete

D. Beams if shear exceeds 4 times allowable shear stress ANS: C

QUESTION –  205

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

A. W – 2P

B. W – P

C. W – P

D. W – 2P

ANS: D

QUESTION –  206

RCC Structures Design Questions and Answers

To have pressure wholly compressive under the base of a retaining wall of width b, the resultant of the weight of the wall and the pressure exerted by the retained, earth should have eccentricity not more than

A. b/3

B. b/4

C. b/5

D. b/6

ANS: D

QUESTION –  207

The diameter of longitudinal bars of a column should never be less than

A. 6 mm

B. 8 mm

C. 10 mm

D. 12 mm

ANS: D

QUESTION –  208

Post tensioning system

A. Was widely used in earlier days

B. Is not economical and hence not generally used

C. Is economical for large spans and is adopted now a days

D. None of these

ANS: D

QUESTION –  209

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

ANS: C

QUESTION –  210

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

A. Minimum bending moment

B. Maximum bending moment

C. Maximum shear force

D. Minimum shear force

ANS: B

QUESTION –  211

The shear reinforcement in R.C.C. is provided to resist

A. Vertical shear

B. Horizontal shear

C. Diagonal compression

D. Diagonal tension

ANS: D

QUESTION –  212

A simply supported beam 6 m long and of effective depth 50 cm, carries a uniformly distributed load 2400 kg/m including its self weight. If the lever arm factor is 0.85 and permissible tensile stress of steel is 1400 kg/cm2, the area of steel required, is

A. 14 cm 2

B. 15 cm2

C. 16 cm2

D. 17 cm2 ANS: C

QUESTION –  213

The anchorage value of a hook is assumed sixteen times the diameter of the bar if the angle of the bend, is

A. 30°

B. 40°

C. 45°

D. All the above

ANS: D

QUESTION –  214

A circular slab subjected to external loading, deflects to form a

A. Semi-hemisphere

B. Ellipsoid

C. Paraboloid

D. None of these

ANS: C

QUESTION –  215

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

A. 5 cm

B. 10 cm

C. 15 cm

D. 20 cm

ANS: B

QUESTION –  216

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

A. Twice the diameter

B. Thrice the diameter

C. Four times the diameter

D. Five times the diameter

ANS: A

QUESTION –  217

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,

A. Is safe in shear

B. Is unsafe in shear

C. Is over safe in shear

D. Needs redesigning ANS: B

QUESTION –  218

If a bent tendon is required to balance a concentrated load W at the centre of the span L, the central dip h must be at least

A. WL /P

B. WL/2P

C. WL/3P

D. WL/4P

ANS: D

QUESTION –  219

If the effective length of a 32 cm diameter R.C.C. column is 4.40 m, its slenderness ratio, is

A. 40

B. 45

C. 50

D. 55

ANS: D

QUESTION –  220

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

A. WL/12 (L – 2D/3)²

B. WL/10 (L + 2D/3)²

C. WL/10 (L – 2D/3)²

D. WL/12 (L – D/3)²

ANS: C

QUESTION –  221

Piles are usually driven by

A. Diesel operated hammer

B. Drop hammer

C. Single acting steam hammer

D. All the above

ANS: D

QUESTION –  222

In a combined footing for two columns carrying unequal loads, the maximum hogging bending moment occurs at

A. Less loaded column

B. More loaded column

C. A point of the maximum shear force

D. A point of zero shear force

ANS: D

QUESTION –  223
If the average bending stress is 6 kg/cm2 for M 150 grade concrete, the length of embedment of a
bar of diameter d according to I.S. 456 specifications, is
A. 28 d
B. 38 d
C. 48 d
D. 58 d
ANS: D
QUESTION –  224
The live load to be considered for an inaccessible roof, is
A. Nil
B. 75 kg/m2
C. 150 kg/cm 2
D. 200 kg/m2
ANS: B
QUESTION –  225
carrying a uniformly distributed load per metre length is suspended at the
A pile of length
centre and from other two points 0.15 L from either end ; the maximum hogging moment will be
A. WL²/15
B. WL²/30
C. WL²/60
D. WL²/90
ANS: D
QUESTION –  226
An R.C.C. roof slab is designed as a two way slab if
A. It supports live loads in both directions
B. The ratio of spans in two directions is less than 2
C. The slab is continuous over two supports
D. The slab is discontinuous at edges
ANS: B

QUESTION –  227

The design of a retaining wall assumes that the retained earth

A. Is dry

B. Is free from moisture

C. Is not cohesive

D. All the above

ANS: D

QUESTION –  228

A foundation rests on

A. Base of the foundation

B. Sub-grade

C. Foundation soil

D. Both B. and C.

ANS: D

QUESTION –  229

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

A. No decay due to termites

B. No restriction on length

C. Higher bearing capacity

D. All the above

ANS: D

QUESTION –  230

For stairs spanning horizontally, the minimum waist provided is

A. 4 cm

B. 6 cm

C. 8 cm

D. 12 cm

ANS: D

QUESTION –  231

The toe projection of foundation slabs is taken

A. As one third of the base

B. As one sixth of overall height of the wall

C. Equal to heel slab

D. Below ground surface

ANS: A

QUESTION –  232

The horizontal portion of a step in a stairs case, is known as

A. Rise

B. Flight

C. Winder

D. Tread

ANS: D

QUESTION –  233

The maximum ratio of span to depth of a cantilever slab, is

A. 8

B. 10

C. 12

D. 16

ANS: C

QUESTION –  234

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

A. Modular ratio method

B. Load factor method

C. Ultimate load method

D. None of these

ANS: A

QUESTION –  235

If permissible working stresses in steel and concrete are respectively 1400 kg/cm2 and 80 kg/cm2 and modular ratio is 18, in a beam reinforced in tension side and of width 30 cm and having effective depth 46 cm, the lever arms of the section, is

A. 37 cm

B. 38 cm

C. 39 cm

D. 40 cm

ANS: D

QUESTION –  236

A pre-stressed concrete member

A. Is made of concrete

B. Is made of reinforced concrete

C. Is stressed after casting

D. Possesses internal stresses

ANS: D

QUESTION –  237

A flat slab is supported

A. On beams

B. On columns

C. On beams and columns

D. On columns monolithically built with slab

ANS: D

QUESTION –  238

A foundation is called shallow if its depth, is

A. One-fourth of its width

B. Half of its width

C. Three-fourth of its width

D. Equal to its width

ANS: D

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