What does the term “reinforcement” in concrete refer to?
A Water content
B Cement particles
C Steel bars or mesh
D Concrete mix design
Reinforcement refers to steel bars or mesh embedded in concrete to enhance its tensile strength. Concrete is strong in compression but weak in tension, so reinforcement helps it resist tensile stresses and increases its overall strength.
What is the main function of a beam in reinforced concrete?
A To support foundations
B To resist bending
C To resist shear
D To resist axial load
Beams in reinforced concrete structures are designed primarily to resist bending, which occurs when they are subjected to loads. The bending strength is provided by the reinforcement embedded in the beam, allowing it to carry loads safely.
What is the typical span-to-depth ratio of a deep beam?
A 2:1
B 1:3
C Greater than 4
D Less than 2
Deep beams have a span-to-depth ratio of less than 2. They behave differently from regular beams, exhibiting significant shear deformations, and require special design considerations, such as additional shear reinforcement.
What is the purpose of using a pile foundation?
A To transfer loads to weaker soil
B To make the building lightweight
C To reduce construction cost
D To improve aesthetic appeal
Pile foundations are used to transfer loads from a structure to deeper, stronger soil or rock layers when the surface soil is too weak or compressible. They provide stability and prevent settlement.
What is the function of a beam-column joint in a structure?
A To improve durability
B To resist axial forces
C To transfer loads between beams and columns
D To resist bending moments
Beam-column joints are critical for transferring loads between beams and columns, ensuring structural stability. Proper detailing of these joints is necessary to prevent failure, particularly in seismic-resistant structures.
What does “creep” in concrete refer to?
A Gradual deformation under constant load
B Cracking due to moisture
C A sudden failure under load
D Shrinkage of concrete
Creep refers to the slow and continuous deformation of concrete under sustained loads over time. It is a time-dependent phenomenon that can cause excessive deflection and stress redistribution in structures.
What is the main characteristic of a one-way slab?
A Has high load-carrying capacity
B Used in high-rise buildings
C Supported on all four sides
D Transfers loads in one direction
A one-way slab is supported on two opposite sides and transfers loads primarily in one direction. It is typically used when the length-to-width ratio is large, and the slab acts as a beam in one direction.
What is the primary cause of cracking in concrete?
A Low water-cement ratio
B Shrinkage during curing
C High compressive strength
D Excessive heat
Cracking in concrete is often caused by shrinkage during the curing process, as the concrete loses moisture and volume. Other factors include thermal stresses and improper curing conditions.
What is the minimum percentage of reinforcement required for reinforced concrete slabs?
A 0.5%
B 1%
C 2%
D 1.5%
The minimum reinforcement required in concrete slabs is typically around 0.5% of the slab’s cross-sectional area. This ensures that the slab can resist tensile forces and perform effectively under load.
Which concrete grade is typically used for pavement construction?
A M15
B M30
C M20
D M10
M20 grade concrete, with a compressive strength of 20 MPa, is commonly used in pavement construction due to its good balance of strength and cost. It provides sufficient durability for moderate traffic loads.
What is the purpose of the working stress method in reinforced concrete design?
A To reduce material cost
B To predict failure modes
C To calculate ultimate strength
D To limit stresses under service loads
The working stress method is used to design reinforced concrete structures by ensuring that the stresses under service loads remain within permissible limits. This method focuses on elastic behavior and avoids excessive deflections or cracking.
What does “ductile detailing” mean in earthquake-resistant design?
A To prevent energy dissipation
B To allow large deformations without failure
C To reduce the cost of construction
D To increase stiffness
Ductile detailing involves designing reinforced concrete structures to withstand large deformations during an earthquake without experiencing sudden failure. This enhances energy dissipation, reducing the risk of collapse and protecting building occupants.
What is the role of a flat slab in reinforced concrete construction?
A To eliminate beams
B To transfer axial loads
C To reduce material cost
D To resist shear forces
Flat slabs are used to eliminate beams, providing a flat ceiling surface. This reduces construction time, simplifies the design, and allows flexible partitioning of spaces without the need for beams in the floor system.
What is the purpose of mix design in concrete?
A To select the color of concrete
B To improve the workability of concrete
C To control the quality and strength of concrete
D To increase the reinforcement
Mix design is the process of selecting appropriate proportions of cement, water, aggregates, and admixtures to achieve the desired strength, durability, and workability of concrete for a specific application.
What does “punching shear” refer to in reinforced concrete slabs?
A Shear due to torsion
B Shear failure around columns due to concentrated loads
C Shear from bending moments
D Shear caused by external forces
Punching shear occurs when concentrated loads from columns create high shear stresses around the column area in flat slabs. Without proper reinforcement, this can lead to sudden and catastrophic failure of the slab.