Important R.C.C Questions for Exams and Interview

Questions with Answers:

• • The pitch of the stair should be between 25 to 40 degree.

• • The minimum and maximum value of cross‐sectional area of longitudinal reinforcement for column are 0.8 % and 6% respectively.

• • The longitudinal bars in columns shall not be less than 12mm in diameter.

• • A R.C.C column is said to be short if length to diameter ratio is less than 15.

• • In the design of Doubly Reinforced Beams, if actual neutral axis is greater than critical neutral axis, the section is over reinforced section.

• • In Marcus method of designing two way slabs, thickness of slab is generally taken to be 1/30 of shorter span.
  • Bottom bars under the columns are extended into the interior of the footing slab to a distance greater than 42 diameters from the outer edge of the column.

  •  In the toe slab of a retaining wall, reinforcement is provided at the bottom of the slab.

• • The concrete work for the following i.e. floors, root slabs and D.P.C of specified thickness are measured in square meters.

• • Plastic strain is generally 10 to 15 times the elastic strain.
  • The minimum number of main steel bars provided in R.C.C rectangular columns is 4, circular columns is 6 and octagonal columns is 8.

• • Ultimate load method of designing a R.C.C structure w.r.t. elastic theory method(working stress method) is more economical.
  • The effective span of a simply supported slab, is clear distance between the inner faces of the walls plus twice the thickness of the wall.
  • In the stem of a retaining wall, reinforcement is provided near the earth side.

• • The moment of resistance of a balanced reinforced section is obtained by multiplying the lever arm with either compressive or tensile force.

• • The section is called under reinforced section when Xu < Xu max.
  • In the heel slab of a retaining wall, reinforcement is provided at the top of the slab.
• • Spacing of longitudinal bars measured along the periphery of the column shall not exceed 300mm.

Reinforced Concrete (R.C.C) is a widely used construction material in civil engineering. It is a composite material that combines the strength of concrete and the tensile strength of steel reinforcement. In competitive exams, questions related to R.C.C are often asked to assess the candidate’s knowledge and understanding of this important construction material. In this comprehensive response, we will discuss some important R.C.C questions that are commonly asked in competitive exams.

1. What is R.C.C?
   Reinforced Concrete (R.C.C) is a composite material made up of concrete and steel reinforcement. The concrete provides compressive strength, while the steel reinforcement provides tensile strength to resist cracking and bending forces. R.C.C is extensively used in the construction of buildings, bridges, dams, and other structures due to its high strength and durability.

2. What are the advantages of using R.C.C?
   R.C.C offers several advantages over other construction materials. Some of the key advantages include:

– High strength: R.C.C has excellent compressive strength, making it suitable for carrying heavy loads.
– Versatility: R.C.C can be molded into various shapes and sizes, allowing for flexible design options.
– Durability: R.C.C structures have a long service life and can withstand harsh environmental conditions.
– Fire resistance: R.C.C has good fire resistance properties, making it suitable for fire-prone areas.
– Cost-effectiveness: R.C.C is relatively cost-effective compared to other construction materials.

1. What are the components of R.C.C?
   The components of R.C.C include:

– Cement: It acts as a binding agent that holds the aggregates together.
– Aggregates: These include coarse aggregates (such as crushed stone or gravel) and fine aggregates (such as sand).
– Water: It is required for the hydration process of cement.
– Steel reinforcement: It provides tensile strength to resist bending forces.

1. What is the role of steel reinforcement in R.C.C?
   Steel reinforcement plays a crucial role in R.C.C structures. It helps to resist tensile forces, prevent cracking, and enhance the overall strength and durability of the structure. The steel reinforcement is placed strategically within the concrete to counteract the tensile stresses that occur due to bending or flexing forces.

2. What are the different types of steel reinforcement used in R.C.C?
   The commonly used types of steel reinforcement in R.C.C include:

– Mild Steel Bars (MS bars): These are plain round bars with low carbon content and are commonly used for general construction purposes.
– High Strength Deformed Bars (HSD bars): These bars have deformations on their surface, which provide better bonding with concrete and higher tensile strength.
– TMT Bars: Thermo-Mechanically Treated (TMT) bars are widely used due to their superior strength, ductility, and corrosion resistance.

1. What is the significance of cover in R.C.C structures?
   The cover refers to the distance between the outer surface of the concrete and the nearest surface of the steel reinforcement. It is essential to provide an adequate cover to protect the steel reinforcement from corrosion, fire, and other environmental factors. Insufficient cover can lead to premature deterioration of the structure and compromise its strength.

2. What is the difference between one-way and two-way slabs in R.C.C?
   One-way slabs are designed to carry loads primarily in one direction, either along their longer span or shorter span. They are supported on two opposite sides by beams or walls. Two-way slabs, on the other hand, are designed to carry loads in both directions along their longer span and shorter span. They are supported on all four sides by beams or walls.

3. What is the concept of modular ratio in R.C.C design?
   The modular ratio is a factor used in the design of R.C.C structures to determine the equivalent stress in concrete and steel. It is the ratio of the modulus of elasticity of steel (Es) to the modulus of elasticity of concrete (Ec). The modular ratio helps in proportioning the steel reinforcement and concrete to ensure that both materials work together efficiently.

4. What is the difference between working stress design and limit state design in R.C.C?
   Working stress design (WSD) is an older method of R.C.C design that considers the structure’s behavior under working loads. It ensures that the stresses in the structure remain within permissible limits. Limit state design (LSD), on the other hand, is a more advanced approach that considers both ultimate limit state (ULS) and serviceability limit state (SLS). LSD aims to ensure the safety, durability, and functionality of the structure under all possible load conditions.

5. What are the different methods for testing the quality of R.C.C?
   Several tests are conducted to assess the quality of R.C.C. Some commonly used tests include:

– Compressive strength test: This test determines the compressive strength of concrete cubes or cylinders.
– Tensile strength test: It measures the tensile strength of concrete using a split tensile test or flexural test.
– Reinforcement bond test: This test evaluates the bond strength between steel reinforcement and concrete.
– Non-destructive testing (NDT): NDT methods like ultrasonic testing, rebound hammer test, and cover meter test are used to assess the quality and integrity of R.C.C structures without causing damage.

In answering this question, I have relied on authoritative reference publications and domain names. The top 3 authoritative reference publications or domain names used in answering this question are:

1. “Design of Reinforced Concrete Structures” by S. Ramamrutham
2. “Reinforced Concrete Design” by Devdas Menon and S. Pillai
3. “Civil Engineering Portal” (www.engineeringcivil.com)

These sources provide comprehensive information on R.C.C, including its properties, design principles, and testing methods.

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