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All questions of RCC & Prestressed Concrete for Civil Engineering (CE) Exam

The critical section for determining the maximum bending moment for footing supporting a concrete column is located:
  • a)
    At the face of column
  • b)
    Halfway between the face of column and centre line
  • c)
    At a distance equal to effective depth of footing from the face of column
  • d)
    None of these
Correct answer is option 'A'. Can you explain this answer?

Sagnik Sen answered
The critical section for determining the maximum bending moment for footing supporting a concrete column is located at the face of the column. This is because the maximum bending moment occurs at the location where the column is fixed to the footing, which is at the face of the column. The bending moment is caused by the eccentricity of the column load with respect to the footing, which creates a moment about the fixed end of the column.

The bending moment is calculated by multiplying the column load by the eccentricity of the load with respect to the footing. The eccentricity is the distance between the center of the column and the point of application of the load on the footing. The maximum bending moment occurs at the face of the column because this is where the eccentricity is maximum.

The design of the footing must take into account the maximum bending moment at the face of the column. The footing must be designed to resist this moment by providing sufficient depth and reinforcing steel. The reinforcement should be placed in the tension zone of the footing to resist the bending moment.

In summary, the critical section for determining the maximum bending moment for footing supporting a concrete column is located at the face of the column because this is where the eccentricity of the column load with respect to the footing is maximum. The design of the footing must take into account this maximum bending moment and provide sufficient depth and reinforcement to resist it.
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The load factors for live and dead load are taken respectively as:
  • a)
    1.5 and 2.2
  • b)
    2.2 and 1.5 
  • c)
    1.5 and 1.5
  • d)
    2.2 and 2.2
Correct answer is option 'C'. Can you explain this answer?

Shail Rane answered
The load factors for live load and dead load shall be taken as 1.5 and 1.5 respectively.
IS 456:2000 (page no 68 table no 18)
"For the limit states of serviceability the values of Y1, given in this table are applicable for short-term effects. While assessing the long-term effects due to creep the dead load and that part of the live load likely to be permanent may only be considered."

Deep beams are designed for
  • a)
    Shear force only
  • b)
    Bending moment only
  • c)
    Both shear force and bending moment
  • d)
    Bearing
Correct answer is option 'B'. Can you explain this answer?

Abhay Banerjee answered
Deep beams are structural elements loaded as simple beams in which a significant amount of the load is carried to the supports by a compression force combining the load and the reaction. As a result, the strain distribution is no longer considered linear, and the shear deformations become significant when compared to pure flexure.
In view of ample shear strength, deep beams are primarily recommended as transfer girders. These members transfer loads through-loading face to supports in the transverse direction. The deep horizontal members predominantly fail in shear rather than flexure. These beams are characterized with small span-to-depth ratio. Pile caps, corbel, brackets, foundation walls and off-shore structures are few examples of RC deep beams.
According to IS 456-2000 a beam shall be deemed to be a deep beam when the ratio of effective span-to-overall depth, l/D is less than:
1) 2.0, for simply supported beam; and
2) 2.5, for a continuous beam.
Though different codes define deep beams in different clear span-to-depth ratios, as a general rule deep beams are recognized by their relatively small span-to-depth ratio.
Hence, Deep beams are designed for bending moment and checked for shear.

The design shear stress in reinforced cement concrete depends on 
  • a)
    Characteristics strength of concrete
  • b)
    Percentage of longitudinal tensile reinforcement
  • c)
    Characteristic strength of steel
  • d)
    Both (a) and (b)
Correct answer is option 'D'. Can you explain this answer?

Sreemoyee Joshi answered
Recent laboratory experiments confirmed that reinforced concrete in beams has shear strength even without any shear reinforcement. This shear strength (τc) depends on the grade of concrete and the percentage of tension steel in beams. The maximum shear strength of reinforced concrete depends on the grade of concrete only. (Reference IS 456, clause 40.2.1 and 40.2.3 respectively)

A doubly reinforced beam is considered less economical than a singly reinforced beam because:
  • a)
    Shear reinforcement is more
  • b)
    Compressive steel is under stressed
  • c)
    Tensile steel required is more than that for balanced section
  • d)
    Concrete is not stressed to its full value
Correct answer is option 'B'. Can you explain this answer?

Anmol Roy answered
Explanation
  • The correct answer, "Compressive steel is under stressed," is considered the crux of why a doubly reinforced beam is less economical than a singly reinforced beam because, in this configuration, the additional steel provided on the compression side does not contribute as effectively as the tensile reinforcement.
  • The compressive steel, being under-stressed, implies that it does not work to its full potential, leading to an inefficient use of material which makes the beam design less cost-effective compared to a singly reinforced beam where materials are generally utilized more efficiently.

In case of beams in RCC members, the flexural crack is formed at:
  • a)
    Mid span
  • b)
    Quarter Span
  • c)
    Near support
  • d)
    None of above 
Correct answer is option 'A'. Can you explain this answer?

Sarthak Kulkarni answered
The types and formation of cracks depends on the span-to-depth ratio of the beam and loading. These variables influence the moment and shear along the length of the beam. For a simply supported beam under uniformly distributed load, without prestressing, three types of cracks are identified.
1) Flexural cracks: These cracks form at the bottom near the mid-span and propagate upwards.
2) Web shear cracks: These cracks form near the neutral axis close to the support and propagate inclined to the beam axis.
3) Flexure shear cracks: These cracks form at the bottom due to flexure and propagate due to both flexure and shear.

The effective span, of cantilever slab at the end of a continuous slab is:
  • a)
    Clear span + effective depth of the slab
  • b)
    Clear span + half of the effective depth of the slab
  • c)
    Length up to face of support + half of the effective width
  • d)
    Length up to the centre of the support
Correct answer is option 'C'. Can you explain this answer?

Engineers Adda answered
Explanation
 

  • Cantilever Span: The effective span of a cantilever slab at the end of a continuous slab is the length up to the face of the support plus half of the effective width. This is because the cantilever slab is supported at one end and extends beyond the support.

  • Effective Span Calculation: To calculate the effective span, you need to consider the length up to the face of the support plus half of the effective width of the slab. This will give you the distance that the cantilever slab can effectively span without additional support.

  • Importance: Determining the effective span of a cantilever slab is important for structural design and ensuring that the slab can support the required loads without failing.


    •  

The shear strength can be ensured in a beam by providing:
  • a)
    Binding wire on main bar
  • b)
    High strength deformed bars 
  • c)
    Rounded aggregates 
  • d)
    Stirrups
Correct answer is option 'D'. Can you explain this answer?

Rohan Singh answered
Vertical or inclined stirrups provide shear resistance to members. Bent up bars are also used to provide shear resistance upto certain limit. 

The Design ultimate load on the short axially loaded column is computed by which of the following equation?
where,
fck = Characterstics strength of concrete
fy = characterstic strength of steel
Ac = Area of concrete in column cross-section
Asc = Area of steel in column in compression
  • a)
    0.4fck Asc + 0.67fy Ac
  • b)
    0.43fck Ac + 0.87fy Asc
  • c)
    0.4fck Ac + 0.67fy Asc
  • d)
    0.4fck Ac + 0.87fy Asc
Correct answer is option 'C'. Can you explain this answer?

Sahana Choudhary answered
As per IS 456 : 2000 In the Design of compression members the ultimate load on the short axially loaded column is:
Pu = 0.4fck Ac + 0.67fy Asc
where,
fck = Characterstics strength of concrete
fy = characterstic strength of steel
Ac = Area of concrete in column cross-section
Asc = Area of steel in column in compression

Which one of the following represents the ratio of volume of helical reinforcement to volume of core if  = 1, concrete is M 20 and steel is Fe 415.
  • a)
    0.024
  • b)
    0.048
  • c)
    0.054
  • d)
    0.060
Correct answer is option 'B'. Can you explain this answer?

Anshul Kumar answered
As per IS 456:2000, clause 39.4.1, the ratio of volume of helical reinforcement to the volume of core shall not be less than   So, ratio is 1 × 20/415 = 0.048 

Reinforcement bars are generally bent:
  • a)
    By heating
  • b)
    Welding
  • c)
    Manually using lever
  • d)
    By dies and jigs
Correct answer is option 'C'. Can you explain this answer?

Sreemoyee Chauhan answered
Reinforcement bars are generally bent by manual levers instead of heating because heating reduces the strength of bar. As Per IS 2502:1963, bending of bars may be done either by improvised means or by hand-operated machines and by power operated bender.

Which of the following statements is true?
A. Most of the loads applied to a building are environmental load.
B. Most of the loads are dead followed by live loads.
  • a)
    Only A
  • b)
    Only B
  • c)
    Both A and B
  • d)
    Neither A nor B
Correct answer is option 'B'. Can you explain this answer?

Rohan Singh answered
Most of the loads applied to the buildings are mainly dead and live loads for buildings located in zone II, III etc. But it, Building is located in Zone IV and is multi-storeyed building then effect of earthquake loads and wind loads all also taken in to consideration. Environmental loads are not all time applied to the structure, or they are uncertain in nature

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
Correct answer is option 'C'. Can you explain this answer?

Rohan Singh answered
Stiffness criteria is associated with A-value and A-value as per IS 456:2000 are:
1. Cantilever beam: 7
2. Simply supported beam: 20
3. Continuous beam: 26

In a rear counterfort retaining wall, the main reinforcement is provided on the
  • a)
    bottom face in front counterfort
  • b)
    inclined face in front counterfort
  • c)
    bottom face in back counterfort
  • d)
    inclined face in back counterfort
Correct answer is option 'D'. Can you explain this answer?

Sankar Dasgupta answered
Counterforts are firmly attached to the face slab as well as the base slab. The earth pressure acting on the face slab is transferred to the counterfort which deflects as vertical cantilever. The back of rear counterfort comes under tension and the front face is under compression. So the inclined (back) face of the rear counterfort should be provided with main reinforcement.

Choose the correct statement regarding reinforcement detailing:
  • a)
    Lap splices, in general, shall not be used for bars larger than 36 mm diameter
  • b)
    For two or more rows of the bars, the bars shall be vertically in line
  • c)
    The cover for reinforcement in footing shall not be less than 50 mm.
  • d)
    All of the above
Correct answer is option 'D'. Can you explain this answer?

Gowri Singh answered
As per IS 456:2000,
1. Lap splicing of reinforcement bar more than 36 mm in diameter should be avoided. In case such bars have to be lapped then they should be welded. (Reference IS456 clause 25.2.5).
2. Where there are two or more rows of bars, the bars shall be vertically in line and the minimum vertical distance between the bars shall be 15 mm, two third the maximum nominal size of aggregate or maximum size of bars, whichever is greater.
3. The minimum nominal cover for footing shall not be less than 50 mm.

In a simply supported slab, alternate bars are curtailed at:
  • a)
    1/5 of the span
  • b)
    1/6 of the span
  • c)
    1/7 of the span
  • d)
    1/8 of the span
Correct answer is option 'C'. Can you explain this answer?

Rohan Singh answered
To economize the design of a flexural member, the tensile bars are curtailed at the section beyond which it is no longer required to resist flexure. In case of Simply Supported slab, alternate bars are curtailed at 1/7 of the span value.

If the diameter of main reinforcement in a slab is 16 mm, the concrete cover to main bar according to IS 456:2000 is:
  • a)
    12 mm
  • b)
    14 mm
  • c)
    16 mm
  • d)
    20 mm
Correct answer is option 'D'. Can you explain this answer?

Parth Patel answered
According to IS 456: 2000, minimum nominal cover to all bars in the slab is 20mm. According to new code, nominal cover does not depend upon the diameter of bar used.

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
Correct answer is option 'C'. Can you explain this answer?

Aditya Jain answered
The nominal maximum size of coarse aggregate should be as large as possible within the limits specified but in no case greater than one-fourth of the minimum thickness of the member, provided that the concrete can be placed without difficulty so as to surround all reinforcement thoroughly and fill the comers of the form, For most work, 20 mm aggregate is suitable. Where there is no restriction to the flow of concrete in to sections, 40 mm or larger size may be permitted. In concrete elements with thin sections, closely spaced reinforcement or small cover, consideration should be given to the use of 10mm nominal maximum size.

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
Correct answer is option 'D'. Can you explain this answer?

Anshul Kumar answered
The panel with drops is 1.25 to 1.50 times thicker than the slab beyond the drop. The minimum slab thickness is 125 mm or L/36 for interior continuous panels without drops and end panels with drops or L/32 for end panels without drops or L/40 for interior continuous panels with drops. The length L is the average length of the panel.

Span to effective depth ratio for a continuous beam with steel grade of Fe 415 should not be more than: -
  • a)
    7
  • b)
    20
  • c)
    26
  • d)
    48
Correct answer is option 'C'. Can you explain this answer?

Pranavi Choudhury answered
It is necessary to impose a check on the magnitude of deflection in a structural member:
a) To ensure that the extent of deflection does not adversely affect the appearance or efficiency of the structure or finishes or partition etc.
b) To prevent structural behaviour of the member being different from the assumption made in the design. As per IS 456:2000, for beams and slabs, the vertical deflection limits may be assumed to be satisfied, provided that the span to depth ratio are not greater than the values obtained as below: 

If the permissible compressive and tensile stresses in a single reinforced beam are 50 kg/cm2 and 1400 kg/cm2 respectively and the modular ratio is 18, the percentage of the steel required for an economic section, is
  • a)
    0.496%
  • b)
    0.596%
  • c)
    0.696%
  • d)
    None of these
Correct answer is option 'C'. Can you explain this answer?

Gowri Singh answered
Taking Moment of area of tension and compression zone for a singly reinforced beam:
Where,
Xc = critical depth or economic depth of neutral axis
m = modular ratio
Ast = area of steel required for balanced section
 
m = 18
c = 50 kg/cm2
t = 1400 kg/cm2

__________ is the type of concrete in which internal stresses are intentionally induced in a planned manner such that the stresses resulting from the superimposed loads get counteracted to a desired degree.
  • a)
    Post-stressed concrete
  • b)
    Intra-stressed concrete
  • c)
    Curvature concrete
  • d)
    Pre-stressed concrete
Correct answer is option 'D'. Can you explain this answer?

Bhaskar Mukherjee answered
The principle behind prestressed concrete is that compressive stresses induced by high-strength steel tendons in a concrete member before loads are applied will balance the tensile stresses imposed in the member during service.
A prestressed concrete member is one in which there have been introduced internal stresses of such a magnitude, and also distribution, that the stresses resulting from external loading are counteracted to a desired degree. By doing this, Nearly the full capacity of the concrete in compression can be used over entire depth under full loading.

As stipulated in IS: 456 – 2000, some assumptions are considered in the computation of ultimate flexural strength of reinforce concrete section. Of the four options given below, the odd one is to be marked.
  • a)
    Plain sections normal to the axis remain plain after bending.
  • b)
    The relationship between compressive stress distributions in concrete may be assumed to be rectangle, trapezoid, parabola or any other shape which results in prediction of strength in substantial agreement with test results.
  • c)
    The tensile strength of concrete is ignored
  • d)
    The maximum strain in concrete at the extreme compression fiber is assumed as 0.003 in flexure.
Correct answer is option 'D'. Can you explain this answer?

Moumita Rane answered
The maximum strain in concrete at the extreme compression fiber is assumed as 0.0035 in flexure.

For a continuous slab of 3 m × 3.5 m size, the minimum overall depth of slab to satisfy vertical deflection limits for the grade of steel FE415 is-
  • a)
    5 cm
  • b)
    7.5 cm
  • c)
    10 cm
  • d)
    12 cm
Correct answer is option 'C'. Can you explain this answer?

Arnab Saini answered
 
For high strength deformed bars of grade Fe415:
For mild steel reinforcement.
where, L is the shorter span of slab
d is overall depth of the beam
d ≥ 9.37 cm = 10 cm

The working stress method of design of RC members is known as:-
  • a)
    Non-deterministic approach
  • b)
    Deterministic approach
  • c)
    Probabilistic approach 
  • d)
    None of the above
Correct answer is option 'B'. Can you explain this answer?

Aditya Jain answered
Working stress method: working stress method is based on elastic theory. Concrete and steel are assumed to act together elastically and follow hook’s law. This method follows a deterministic approach as it assumes that the loads, factor of safety and permissible stresses are accurately known. In this method material strengths are not fully utilised in designing the member.
Limit state method: This method follows a non-deterministic approach as it adopts probable loads and probable strengths of materials as per actual or based on experience or observations depending upon the situations. Material strengths are fully utilised in designing the member.

For a square column, b × b in size, effective depth of the footing being ‘d’, the punching shear is calculated for an area
  • a)
    2b × d
  • b)
    4(bd + d2)
  • c)
    2(bd + d2)
  • d)
    b × 4d
Correct answer is option 'B'. Can you explain this answer?

Rajat Sen answered
The critical section for shear is act at a distance of d/2 from the face of the column. So, the total resisting area which resist that punching shear will be 
= 4(bd + d2).

In R.C footing on soil, the thickness at the edge should not be less than
  • a)
    10 cm
  • b)
    15 cm
  • c)
    20 cm
  • d)
    25 cm
Correct answer is option 'B'. Can you explain this answer?

Yashvi Choudhury answered
According to the Code (CI. 34.1.2):
Code restricts the minimum thickness at the edge of the footing to 150 mm for footings in general (and to 300 mm in the case of pile caps).

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
Correct answer is option 'D'. Can you explain this answer?

Maulik Joshi answered
According to IS 456:2000, the width of the flange of a L-beam should be lesser of
i) The breadth of the rib plus half the sum of the clear distances to the adjacent ribs.
ii) The breadth of the rib plus four times thickness of the slab.

Chapter doubts & questions for RCC & Prestressed Concrete - Civil Engineering SSC JE (Technical) 2025 is part of Civil Engineering (CE) exam preparation. The chapters have been prepared according to the Civil Engineering (CE) exam syllabus. The Chapter doubts & questions, notes, tests & MCQs are made for Civil Engineering (CE) 2025 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests here.

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