Question 1

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

Accepted Answer

The angle of repose of a soil is the maximum angle at which a soil mass remains stable and is measured with respect to the horizontal plane, not the vertical or any other plane.

Question 2

In a doubly-reinforced beam if and is 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

Accepted Answer

The correct relationship for a doubly-reinforced beam, considering the effective depth (d) and the depth of the critical neutral axis (n), is given by mc/t = n/(d - n). This formula is used to calculate the moment of resistance or to design the beam considering the areas of steel in tension (t) and compression (c), and the lever arm (d - n).

Question 3

A raft foundation is provided if its area exceeds the plan area of the building by
A)10 %
B)20 %
C)40 %
D)50%

Accepted Answer

A raft foundation is typically provided if its area exceeds the plan area of the building by 50%. This type of foundation spreads the load of the building over a large area, which is particularly useful in cases where the soil has a low bearing capacity or where the building load is heavy.

Question 4

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

Accepted Answer

The answer of In favourable circumstances a 15 cm concrete...

Question 5

If p₁ is the vertical intensity of pressure at a depth h on a block of earth weighing w per unit p² is A) wh(1?cos?)/(1+sin?) B) wh(1?sin?)/(1+sin?) C) wh(1?tan?)/(1+tan?) D) w(1?sin?)/h(1+sin?)

Accepted Answer

The vertical intensity of pressure at a depth h on a block of earth weighing w per unit volume is given by the formula $wh\frac{1-\sin\theta}{1+\sin\theta}$, where $\theta$ is the angle of internal friction of the soil. This formula is derived from the principle of effective stress in soil mechanics, considering the effects of soil cohesion and internal friction on the vertical pressure.

Question 6

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 neutralaxis
D)Moment of the beam section about its neutral axis

Accepted Answer

The intensity of horizontal shear stress is not directly proportional to the moment of the beam section about its neutral axis; it is related to shear force, area, and distance from the neutral axis.

Question 7

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

Accepted Answer

According to IS: 456-1978, the thickness of reinforced concrete footing on piles at its edges is kept less than 30 cm. This is to ensure structural integrity and appropriate load distribution.

Question 8

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/cm² D)11.4 kg/cm²

Accepted Answer

The maximum shear force (V) for a uniformly distributed load (UDL) on a simply supported beam is calculated as V = wL/2, where w is the load per unit length and L is the span length. The maximum shear stress ($\tau_{max}$) in a rectangular section is given by $\tau_{max} = 1.5 \times V / (b \times d)$, where b is the width and d is the effective depth of the beam. Given the lever arm constant is 0.865, it indicates the efficiency of the section in resisting bending moments but does not directly affect the calculation of shear stress in this context. Using the given dimensions and load, the calculation aligns closest with the option that results in a shear stress of approximately 8.3 kg/cm², indicating the correct approach to calculating shear stress in a rectangular beam under a UDL.

Question 9

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%

Accepted Answer

The minimum reinforcement in slabs is 0.15% of the gross sectional area.

Question 10

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

Accepted Answer

The modular ratio is given by the formula 2800/3C, where C is the permissible compressive stress for concrete in bending. This formula accounts for the relationship between the modulus of elasticity of steel and concrete.

Question 11

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°

Accepted Answer

In an R.C.C. beam without shear reinforcement, cracks typically develop at an angle of about 45° to the horizontal. This is because the principal stress direction causing these cracks aligns approximately at this angle when shear failure is imminent.

Question 12

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

Accepted Answer

The answer of Cantilever retaining walls can safely be used...

Question 13

The maximum area of tension reinforcement in beams shall not exceed
A)0.15 %
B)1.5 %
C)4 %
D)1 %

Accepted Answer

The maximum area of tension reinforcement in beams should not exceed 4% of the gross cross-sectional area of the beam. This limit is set to ensure ductility, control cracking, and prevent steel congestion that could impair concrete placement and compaction.

Question 14

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 theabove

Accepted Answer

The width of the flange of a T-beam should be the least among the specified limits: one-third of the effective span of the T-beam, the distance between the centres of T-beams, and the breadth of the rib plus twelve times the thickness of the slab. This ensures optimal structural performance and efficiency.

Question 15

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

Accepted Answer

The ratio of the maximum negative to maximum positive radial moment for a circular slab carrying a uniformly distributed load is 2. This is based on the principles of structural analysis and the behavior of circular slabs under uniform loads.

Question 16

According to I.S. : 456 specifications, the safe diagonal tensile stress for M 150 grade concrete, is A)5 kg/cm² B)10 kg/cm² C)15 kg/cm² D)20 kg/cm²

Accepted Answer

According to IS 456:2000, the safe diagonal tensile stress for M 150 grade concrete is approximately 5 kg/cm².

Question 17

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

Accepted Answer

The width of the flange of a T-beam that can be considered to act effectively with the rib depends on multiple factors including the breadth of the rib, the overall thickness of the rib, and the center to center distance between T-beams. These factors collectively influence the distribution of stresses and the structural behavior of the T-beam in a composite action.

Question 18

The maximum shear stress (qmax) in a rectangular beam is
A)1.25 times the average
B)1.50 timesthe average
C)1.75 timesthe average
D)2.0 times theaverage

Accepted Answer

The answer of The maximum shear stress (qmax) in a...

Question 19

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

Accepted Answer

The effective width of the slab is calculated using the formula Kx (1 - x/l) + bw, which accounts for the position of the load and the geometry of the slab.

Question 20

The length of the straight portion of a bar beyond the end of the hook, should be at least
A)Twice thediameter
B)Thrice thediameter
C)Four times the diameter
D)Seventimes the diameter

Accepted Answer

The answer of The length of the straight portion of...

Quiz 5: Concrete Beam and Structural Design

The angle of repose of a soil is the maximum angle which the outer face of the soil mass makes

In a doubly-reinforced beam if and is the effective depth and is depth of critical neutral axis, the following relationship holds good

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

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

If p1 is the vertical intensity of pressure at a depth h on a block of earth weighing w per unit p2 is

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

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

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

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

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

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

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

The maximum area of tension reinforcement in beams shall not exceed

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

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

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

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

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

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

If p₁ is the vertical intensity of pressure at a depth h on a block of earth weighing w per unit p² is

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