What is the primary purpose of reinforcement in concrete?
A Reduce cost
B Improve appearance
C Increase tensile strength
D Increase density
Concrete is strong in compression but weak in tension. Reinforcement, typically steel bars, is added to concrete to improve its tensile strength. The steel bars resist tensile forces, while the concrete resists compressive forces, making the composite material (reinforced concrete) suitable for structural applications like beams, slabs, and columns.
Which of the following is the most common grade of concrete used in residential buildings?
A M40
B M20
C M10
D M60
M20 grade concrete, with a characteristic compressive strength of 20 MPa, is commonly used in residential buildings. It provides a good balance between strength and cost‐effectiveness for low to medium‐rise structures. Higher grades like M40 or M60 are used for specialized or heavy–load structures.
What is the main function of shear reinforcement in beams?
A Prevent cracking
B Resist bending moments
C Improve durability
D Resist shear forces
Shear reinforcement, such as stirrups or bent–up bars, is provided in beams to resist diagonal tensile stresses caused by shear forces. Without shear reinforcement, beams may fail due to diagonal cracking, especially in regions of high shear stress near supports or concentrated loads.
Which type of slab is supported on all four sides?
A Cantilever slab
B Two–way slab
C Flat slab
D One–way slab
A two–way slab is supported on all four sides, and the load is transferred in both directions (length and width). This type of slab is used when the length–to–width ratio is less than or equal to 2. One–way slabs, on the other hand, transfer load primarily in one direction.
What is the minimum percentage of steel required in a reinforced concrete column?
A 0.8%
B 1.5%
C 1.0%
D 2.0%
As per IS 456:2000, the minimum percentage of steel reinforcement in a column is 0.8% of the gross cross–sectional area. This ensures the column can withstand compressive loads and provides ductility to prevent sudden failure.
What is the purpose of providing cover to reinforcement in concrete?
A Increase strength
B Improve aesthetics
C Prevent corrosion
D Reduce weight
Concrete cover is the layer of concrete provided over the reinforcement to protect it from environmental factors like moisture, chemicals, and fire. Adequate cover prevents corrosion of steel, ensuring the durability and longevity of the structure.
Which of the following is a characteristic of prestressed concrete?
A High tensile strength
B No reinforcement required
C Pre–compression in concrete
D Low compressive strength
Prestressed concrete involves introducing internal stresses into the concrete before it is subjected to external loads. This is achieved by tensioning steel tendons, which compress the concrete, improving its ability to resist tensile stresses and reducing cracking under load.
What is the primary cause of creep in concrete?
A High temperature
B Rapid drying
C Chemical reactions
D Long–term loading
Creep in concrete is the gradual deformation that occurs under sustained long–term loading. It is caused by the slow movement of water within the concrete matrix and the rearrangement of its internal structure. Creep can lead to increased deflection and stress redistribution in structures.
Which limit state ensures the structure remains functional and comfortable for users?
A Fatigue limit state
B Serviceability limit state
C Stability limit state
D Ultimate limit state
The serviceability limit state (SLS) ensures that a structure remains functional, comfortable, and durable under normal use. It includes criteria like deflection, cracking, and vibration, which affect the usability and appearance of the structure but do not compromise its safety.
What is the purpose of bond in reinforced concrete?
A Increase durability
B Reduce shrinkage
C Transfer load between concrete and steel
D Improve workability
Bond refers to the adhesion and mechanical interlock between concrete and reinforcement. It ensures that loads are effectively transferred between the two materials, allowing them to act as a composite unit. Proper bond strength is essential for the structural integrity of reinforced concrete elements.
Which of the following is a common method for designing reinforced concrete structures?
A Elastic method
B Limit state method
C Plastic method
D All of the above
Reinforced concrete structures can be designed using various methods, including the limit state method (most common), elastic method, and plastic method. The limit state method considers both ultimate and serviceability limit states, ensuring safety and functionality.
What is the main purpose of ductile detailing in earthquake–resistant design?
A Improve energy absorption
B Increase stiffness
C Enhance aesthetics
D Reduce weight
Ductile detailing involves designing reinforced concrete structures to undergo large deformations without sudden failure during earthquakes. This improves energy absorption and dissipation, reducing the risk of collapse and enhancing the structure’s ability to withstand seismic forces.
Which type of foundation is used for transferring heavy loads to deep soil strata?
A Raft foundation
B Isolated foundation
C Pile foundation
D Strip foundation
Pile foundations are used to transfer heavy loads from structures to deep, stable soil strata or rock. They are suitable for areas with weak or compressible surface soils and are commonly used in high–rise buildings, bridges, and offshore structures.
What is the primary cause of punching shear in flat slabs?
A Temperature changes
B Bending moments
C Lateral forces
D Concentrated loads
Punching shear occurs in flat slabs due to concentrated loads, such as columns, causing shear stresses around the load area. If not properly designed, it can lead to a sudden failure of the slab around the column.
Which code of practice is commonly used for reinforced concrete design in India?
A IS 456
B IS 1893
C IS 1343
D IS 800
IS 456:2000 is the Indian Standard code of practice for the design and construction of reinforced concrete structures. It provides guidelines for materials, design principles, and construction practices to ensure the safety and durability of concrete structures.