What is the primary purpose of providing stirrups in beams?
A Improve aesthetics
B Resist bending moments
C Increase bond strength
D Resist shear forces
Stirrups are provided in beams to resist shear forces and prevent diagonal cracking. They are typically placed perpendicular to the longitudinal reinforcement and help confine the concrete, enhancing its shear capacity.
Which of the following is a characteristic of prestressed concrete?
A No reinforcement required
B High tensile strength
C Pre–compression in concrete
D Low compressive strength
Prestressed concrete involves introducing internal compressive stresses into the concrete before it is subjected to external loads. This reduces tensile stresses under load, improving crack resistance and load–carrying capacity.
What is the primary purpose of curing in concrete?
A Reduce cost
B Prevent moisture loss
C Increase workability
D Improve aesthetics
Curing ensures proper hydration of cement, preventing moisture loss and enhancing the strength and durability of concrete. It also reduces shrinkage cracks and improves the overall performance of the structure.
Which of the following is a common cause of deflection in slabs?
A Excessive loading
B High reinforcement ratio
C Low water–cement ratio
D Low span–to–depth ratio
Excessive loading is a common cause of deflection in slabs. It leads to bending and deformation, especially if the slab is not properly designed or reinforced to handle the applied loads.
What is the primary purpose of ductile detailing in reinforced concrete?
A Enhance aesthetics
B Increase stiffness
C Improve energy absorption
D Reduce weight
Ductile detailing ensures that reinforced concrete structures can undergo large deformations without sudden failure. This is particularly important in earthquake–resistant design, where energy absorption is critical.
Which of the following is a key factor in the durability of concrete?
A Low compressive strength
B Low permeability
C High water–cement ratio
D High shrinkage
Low permeability is essential for the durability of concrete, as it prevents the ingress of harmful substances like water, chemicals, and gases. Proper mix design and curing help achieve low permeability.
What is the primary purpose of retaining walls?
A Support vertical loads
B Resist lateral earth pressure
C Reduce foundation depth
D Improve aesthetics
Retaining walls are designed to resist lateral earth pressure and hold back soil or other materials. They are commonly used in terrains, highways, and basements to prevent soil erosion and slope failure.
Which of the following is a common method for structural retrofitting?
A Increasing water–cement ratio
B Reducing loads
C Adding new columns
D Applying fiber–reinforced polymers (FRP)
Structural retrofitting involves strengthening existing structures. FRP wrapping is a common technique that enhances the load–carrying capacity and ductility of beams, columns, and slabs without adding significant weight.
What is the primary purpose of pile caps?
A Transfer loads to piles
B Reduce foundation depth
C Improve soil strength
D Increase concrete strength
Pile caps are thick concrete mats that distribute the load from a column or wall to a group of piles. They ensure uniform load transfer and provide stability to the foundation system.
Which of the following is a common cause of cracking in concrete?
A Low water–cement ratio
B High bond strength
C High compressive strength
D Shrinkage
Cracking in concrete is often caused by shrinkage, which occurs due to the loss of moisture during curing. Other causes include thermal stresses, overloading, and inadequate reinforcement.
What is the primary purpose of torsion reinforcement in beams?
A Improve bond strength
B Resist twisting forces
C Reduce deflection
D Resist bending moments
Torsion reinforcement, such as closed stirrups and longitudinal bars, is provided in beams to resist twisting forces caused by eccentric loads or uneven support conditions, preventing structural failure.
Which of the following is a common type of foundation for high–rise buildings?
A Raft foundation
B Strip foundation
C Pile foundation
D Isolated foundation
Pile foundations are commonly used for high–rise buildings to transfer heavy loads to deep, stable soil strata or rock. They provide stability and prevent excessive settlement.
What is the primary purpose of reinforcement detailing?
A Reduce concrete strength
B Ensure proper placement of bars
C Increase shrinkage
D Improve aesthetics
Reinforcement detailing involves specifying the size, spacing, and arrangement of reinforcement bars. It ensures proper load transfer, structural integrity, and compliance with design requirements.
Which of the following is a common cause of deflection in beams?
A Low reinforcement ratio
B Low water–cement ratio
C High bond strength
D High compressive strength
Excessive deflection in beams is often caused by insufficient reinforcement or a low reinforcement ratio. It can also result from overloading, improper design, or inadequate stiffness.
What is the primary purpose of flat slabs in reinforced concrete design?
A Increase deflection
B Reduce bond strength
C Reduce construction time
D Improve aesthetics
Flat slabs are used to reduce construction time and costs by eliminating beams. They provide a flat ceiling surface, allowing flexible partitioning and easier installation of services.