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Question & Answers Series to Civil Engineering for competitive Exams p2

 

Question & Answers Series to Civil Engineering for competitive exams

Question Answer Session for Civil Engineering Competitive Exams

 

 

Question Answer Session for Civil Engineering Competitive Exams

Q1: What is the formula for calculating the bearing capacity of a shallow foundation? 

A1: The formula for calculating the bearing capacity of a shallow foundation is given by: Q = cNc + qNq + 0.5γBNγ where Q is the bearing capacity, 

c is the cohesion of the soil,

 Nc and Nq are bearing capacity factors, 

q is the overburden pressure, 

γ is the unit weight of the soil, 

and B is the width of the foundation.

Q2: What is the significance of the water-cement ratio in concrete mix design? 

A2: The water-cement ratio is a critical parameter in concrete mix design. It determines the strength, workability, and durability of the concrete. A higher water-cement ratio results in a more workable mix but may compromise the strength and durability. Conversely, a lower water-cement ratio improves strength and durability but may make the mix less workable.

Q3: Difference between one-way and two-way slabs

A3: One-way slabs are supported by beams on two opposite sides, and the load is transferred in one direction perpendicular to the supporting beams. Two-way slabs are supported by beams on all four sides, and the load is transferred in two directions perpendicular to each other. Two-way slabs distribute the load more efficiently than one-way slabs and are suitable for larger spans.

Q4: What is the purpose of a retaining wall? 

A4: A retaining wall is a structure designed to resist the lateral pressure of soil or other materials when there is a desired change in ground elevation. The purpose of a retaining wall is to prevent soil erosion, provide stability to slopes, and create usable areas of land by restraining soil and supporting vertical or near-vertical grade changes.

Q5: What is the modulus of elasticity of concrete? 

A5: The modulus of elasticity of concrete, denoted as E, is a measure of its stiffness or ability to deform elastically under load. It represents the ratio of stress to strain within the elastic range of the material. The modulus of elasticity of concrete typically ranges from 28,000 to 40,000 MPa (megapascals).

Q6: What is the difference between flexible pavement and rigid pavement? 

A6: Flexible pavement refers to a type of road construction where the load-bearing capability is provided by the pavement layers working together through flexural strength. It is made up of multiple layers of bituminous materials. 

Rigid pavement, on the other hand, relies on the strength and rigidity of the pavement itself, usually constructed using reinforced concrete slabs.

Q7: What is the purpose of a slump test in concrete work?

 A7: The slump test is performed to assess the workability of freshly mixed concrete. It measures the consistency and fluidity of the concrete mixture. The test involves filling a slump cone with concrete, compacting it, and then removing the cone. The resulting slump or settlement of the concrete is measured and compared to the specified range to ensure proper workability.

Q8: What are the different types of foundations used in civil engineering? 

A8: The different types of foundations commonly used in civil engineering are:

Shallow foundations: Including spread footings, combined footings, and mat foundations.

Deep foundations: Including pile foundations, drilled shafts, and caissons.

Special foundations: Including floating foundations, well foundations, and under reamed piles.

Q9: What is the purpose of a soil compaction test? 

A9: Soil compaction tests are conducted to determine the maximum dry density and optimum moisture content of a soil. These tests provide information about the soil's compaction characteristics and help ensure that the soil is adequately compacted for construction purposes, such as building foundations or road embankments 

Q10: The role of a civil engineer in construction projects is

 A10: Civil engineers play a vital role in construction projects. They are responsible for planning, designing, and supervising the construction of various structures, such as bridges, buildings, dams & roads. They ensure compliance with safety standards, analyze and evaluate project sites, manage resources, and coordinate with other professionals to deliver successful and sustainable construction projects.

Q11: What is the purpose of a sieve analysis test in soil mechanics? 

A11: A sieve analysis test is conducted to determine the particle size distribution of a soil sample. It helps classify the soil into different grain sizes, such as gravel, sand, silt, and clay. The test provides valuable information for designing foundations, determining soil suitability for various engineering purposes, and evaluating soil properties related to drainage, compaction, and permeability.

Q12: What is the difference between ultimate load and working load in structural design? 

A12: In structural design, the ultimate load refers to the maximum load a structure can withstand before it fails or collapses. It is typically used to ensure the safety and structural integrity of a building or other structure. On the other hand, the working load (also known as the service load) represents the actual load or forces that are anticipated during normal use of the structure.

Q13: What is the purpose of a bar bending schedule (BBS) in reinforced concrete construction? 

A13: A bar bending schedule (BBS) is a detailed list that specifies the number, length, shapes, and dimensions of reinforcing bars (rebars) required for a reinforced concrete structure. The BBS is prepared based on the structural drawings and helps in estimating the quantity of steel reinforcement, planning and scheduling fabrication, and ensuring proper placement of rebars during construction.

Q14: What is a bearing capacity failure in soil mechanics? 

A14: Bearing capacity failure in soil mechanics refers to the failure of a foundation or soil under excessive loads, leading to settlement, excessive deformation, or even collapse. It occurs when the applied load exceeds the load-carrying capacity of the soil. It is important to consider the bearing capacity of the soil during foundation design to ensure the stability and safety of the structure.

Q15: The purpose of a geotechnical investigation is

A15: A geotechnical investigation is conducted to gather information about the physical properties and rock layers at a project site & behavior of the subsurface soil. It helps engineers and designers make informed decisions regarding foundation design, slope stability, earthworks, and construction methods. Geotechnical investigations involve field exploration, soil sampling, laboratory testing, and analysis of data to assess soil suitability and determine the potential risks and challenges at a site.

Q16: What are the different types of bridges commonly used in civil engineering? 

A16: The different types of bridges commonly used in civil engineering include:

Beam bridges: Simplest type, with horizontal beams supported at each end.

Arch bridges: Arch-shaped structures that carry loads through compression.

Suspension bridges: Supported by cables hung from towers, with the load transferred to anchorages.

Cable-stayed bridges: Similar to suspension bridges, but with cables connected directly to the deck.

Truss bridges: Built with interconnected triangular units to provide rigidity and strength.

Cantilever bridges: Constructed by extending structures from balanced or anchored arms.

Q17: What is the purpose of a geosynthetic material in civil engineering? 

A17: Geosynthetics are synthetic materials used in civil engineering for various purposes, including drainage,separation, reinforcement, filtration, and erosion control. They are commonly used in geotechnical and hydraulic applications such as landfills,embankments, retaining walls, and erosion control measures. Geosynthetics provide additional strength and improve the performance and durability of geotechnical structures.

Q18: What is the significance of the pH value in concrete? 

A18: The pH value of concrete is an important factor that affects the corrosion of reinforcing steel. Alkalinity, provided by the presence of hydroxide ions (OH-) in concrete, helps to protect the steel from corrosion. A pH value above 9 is considered ideal for maintaining passivity and preventing corrosion of the reinforcement within the concrete.

Q19: What is the difference between stress and strain in structural mechanics? 

A19: In structural mechanics, stress refers to the internal force or load per unit area applied to a material. It is a measure of the intensity of the force within the material.

 Strain, on the other hand, is the measure of the deformation or elongation experienced by a material in response to stress. 

Stress and strain are related through material properties such as modulus of elasticity and Poisson's ratio.

Q20: What are the primary causes of concrete cracks? 

A20: Concrete cracks can occur due to various reasons, including:

Shrinkage: As concrete cures, it undergoes volume changes, leading to shrinkage cracks.

Settlement: Uneven settling of the supporting soil can cause cracks in concrete structures.

Overloading: Excessive loads beyond the design capacity of the concrete can result in cracks.

Temperature changes: Rapid or extreme temperature fluctuations can induce thermal cracks.

Poor construction practices: Inadequate concrete placement, compaction, or curing can contribute to cracking.

Q21: What is the purpose of a construction schedule or Gantt chart? 

A21: A construction schedule or Gantt chart is a visual representation of the planned sequence and duration of activities in a construction project. 

It helps project managers and teams to plan and coordinate tasks, allocate resources, track progress, and manage project timelines effectively. A construction schedule ensures that activities are executed in a timely manner and assists in identifying and resolving potential bottlenecks or delays.

Q22: What is the role of a quantity surveyor in construction projects? 

A22: Quantity surveyors are professionals who are responsible for managing the costs and financial aspects of construction projects. Their roles include estimating project costs, preparing bills of quantities, conducting cost analysis, managing contracts, and ensuring cost control throughout the project lifecycle. Quantity surveyors play a crucial role in cost management, procurement, and financial planning in construction projects.

23. What is the bearing capacity of soil? 

Answer: The bearing capacity of soil is the maximum capacity of the soil to bear the load without failure.

24. What is the formula for the strength of concrete? 

Answer: The strength of concrete is calculated by the formula: Strength = Load / area.

25. The purpose of a retaining wall is

Answer: The purpose of a retaining wall is to retain soil or other materials in a vertical shape.

26. Explain the function of a culvert.

 Answer: It is a structure used to allow water to flow under a road or railway line.

27. The difference between a beam and a column is

 Answer: A beam is a structural member that primarily carries bending and shearing stress, 

while a column is designed to support axial compressive loads.

28. Define 'Hydraulic Gradient.'

 Answer: The slope of the water surface in a container or soil medium in which water flows under the effect of gravity is called Hydraulic Gradient.

29. What do you understand by the term 'Shear Strength'? 

Answer: Shear Strength is the maximum stress that can be applied to a material before it ruptures in shear.

30. The purpose of a water tower is

Answer: A large elevated reservoir or storage tank that holds water to provide a constant pressure and flow of water to the municipal water distribution system.

I hope these questions and answers are helpful for your competitive preparation in civil engineering!


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