Structural Engineer Interview Questions with expert answers: Civil Engineering Questions and Answers

Structural Engineering Interview Questions

1. What is the density of steel?

Approximately 7850 kg/m³.

2. Why do we use only steel for reinforcement in concrete?

Because the expansion and contraction ratio of steel and concrete is the same, therefore contraction and expansion of R.C.C do not disturb the bond between steel and concrete.

3. What is a bar bending schedule (BBS)?

BBS is a document having all data relating to steel bars required for a construction project, including their sizes, lengths, quantities, and bending shapes.

4. What is a cantilever beam?

A beam that is fixed at one end and free at the other, supported only at the fixed end.

5. What is the standard slump for concrete in columns?

Generally, a slump of 75-100 mm is standard for columns.

6. What is the standard compressive strength of 1:2:4 concrete?

Approximately 3000 to 3500 after 28 days.

7. For compressive strength test Concrete cube or cylinder has more strength?

A concrete cube has more strength due to its size and shape.

8. What is the role of aggregates in concrete?

Aggregates provide strength, bulk, and resistance to shrinkage, cracking, and temperature changes.

9. What is the role of Cement in concrete?

Cement is used in concrete as a binding material.

10. What is the role of sand in concrete?

Sand is used in concrete as filler material.

11. What is the purpose of admixtures in concrete?

Admixtures are added to modify properties such as workability, curing time, and durability.

12. What is the difference between reinforced and prestressed concrete?

Reinforced concrete uses steel bars to resist tension, while prestressed concrete is pre-tensioned or post-tensioned to improve load-bearing capacity.

13. What are the types of beams used in construction?

Common types include simply supported beams, cantilever beams, continuous beams, and composite beams.

14. What are shear forces and bending moments in a beam?

Shear forces act perpendicular to the beam, causing sliding, while bending moments cause the beam to bend.

15. How do civil engineers ensure the durability of concrete structures?

Civil engineers ensure durability through proper mix design, adequate curing, use of quality materials, and regular maintenance.

16. What is the purpose of reinforcement in concrete structures?

To increase the tensile strength of concrete and bond of concrete.

17. What is the standard lap length in steel reinforcement?

Lap length in reinforcement is calculated by multiplying the diameter of steel by a number between 25 to 40, depending on different concrete structures (overlap = 25 to 40 x dia).

18. What is a one-way slab versus a two-way slab?

A one-way slab is supported on two sides and spans in one direction, while a two-way slab is supported on all four sides and spans in both directions.

19. What is yield strength and ultimate strength in steel?

Yield strength is the stress at which a material begins to deform plastically, while ultimate strength is the maximum stress a material can withstand before failure.

20. What is the standard suitable temperature for concrete pouring?

Standard suitable temperature for concrete pouring is between 10°C (50°F) and 32°C (89.6°F).

21. What are the different types of cement used in concrete production?

Ordinary Portland Cement, Portland Pozzolana Cement, Rapid Hardening Cement, Sulphate Resisting Cement, and Fly Ash Cement, etc.

22. Describe the process of retrofitting a concrete structure for enhanced performance.

Retrofitting involves assessing the existing structure, designing improvements (like adding reinforcements), and applying these changes to increase strength and durability.

23. What is an expansion joint in concrete structures?

Expansion joint is a structural space that allows concrete structure’s movement due to thermal expansion and contraction.

24. What is a construction joint in concrete structures?

Construction joints provide a break in the continuity of a concrete structure, typically used when pouring cannot be completed in one operation.

25. What is the difference between grade #60 and grade #40 steel?

Grade #60 steel has a yield strength of 60,000 psi, while grade #40 steel has a yield strength of 40,000 psi.

26. What is the concept of creep in concrete structures?

Creep is the gradual deformation of concrete under sustained load over time, leading to deflection.

27. What is the meaning of fatigue in steel members?

Fatigue means weakening of steel due to repeated loading and unloading cycles, which can lead to failure.

28. What is structural redundancy?

Structural redundancy is the incorporation of additional structural elements to ensure that if one element fails, the structure can still carry loads safely.

29. What is the maximum limit of the throughput of concrete to avoid segregation?

The maximum limit of the throughput of concrete to avoid segregation is typically around 1.5 meters (5 feet).

30. What is segregation of concrete?

Segregation means separation of the coarse aggregate from the cement paste in concrete due to improper mixing and handling.

31. What is the suitable removal time of concrete formwork for different concrete structures?

Formwork can typically be removed after 24 to 48 hours for vertical structures and after 7 days for horizontal structures, depending on the conditions.

32. What is formwork?

Formwork is a temporary structure used to mold concrete into the desired shape while it sets.

33. How can we increase the initial setting time of concrete?

We can increase the initial setting time of concrete by using retarders, reducing the water-cement ratio, or lowering the temperature of the mix.

34. What is the initial setting time of cement?

Initial setting time of cement is the time taken for the cement paste to start losing its plasticity, usually within 30 to 45 minutes.

35. What is the final setting time of cement?

Final setting time of cement is the time taken for the cement paste to fully lose its plasticity and gain sufficient hardness, usually within 10 hours.

36. How can we check the setting time of cement?

The setting time of cement can be checked using a Vicat apparatus, which measures the penetration of a needle into the cement paste.

37. What are the factors affecting the setting time of cement?

Factors affecting setting time include temperature, water-cement ratio, admixtures, and cement composition.

38. What is the role of reinforcement in RCC?

Reinforcement in RCC provides tensile strength and prevents cracking under tension loads.

39. What are the methods of curing concrete?

Common methods include water curing, steam curing, membrane curing, and curing compounds.

40. What is the purpose of curing concrete?

Curing concrete ensures that it retains moisture for hydration, allowing it to achieve the desired strength and durability.

41. What are the different methods of curing?

Different methods include water curing, membrane curing, steam curing, and curing compounds.

42. What is concrete slump?

Concrete slump is a measure of the consistency or workability of fresh concrete, determined using a slump cone test.

43. What is workability in concrete?

Workability refers to the ease with which concrete can be mixed, placed, and finished without segregation.

44. How can workability of concrete be increased?

Workability can be increased by adding water, using admixtures like plasticizers, and improving aggregate grading.

45. What are the causes of poor workability?

Causes include low water content, poor aggregate grading, excessive cement content, and harsh mix proportions.

46. What is shrinkage in concrete?

Shrinkage is the reduction in volume of concrete due to loss of moisture, leading to cracks and deformation.

47. What is an isolated footing?

An isolated footing is a type of shallow foundation used to support individual columns, spreading the load to the soil below.

48. What is the purpose of curing compounds in concrete?

Curing compounds help retain moisture in concrete, aiding in the hydration process for strength development.

49. What is concrete bleeding?

Concrete bleeding occurs when water rises to the surface of the fresh mix due to the settlement of solid particles, leading to weak surfaces.

50. What is plastic shrinkage?

Plastic shrinkage is the rapid evaporation of water from the surface of freshly placed concrete, causing cracks before it hardens.

51. What are the causes of segregation?

Causes include excessive vibration, improper mix design, overuse of water, and high drop height during placement.

52. What is rebar detailing?

Rebar detailing is the process of preparing shop drawings for the placement, bending, and installation of reinforcing steel bars in concrete structures.

53. What is the purpose of reinforcement hooks?

Reinforcement hooks provide anchorage and prevent slippage of bars, improving the bond between steel and concrete.

54. What is water cement ratio?

Water cement ratio is the ratio of the weight of water to the weight of cement in a concrete mix, affecting strength and workability.

55. What is the modulus of elasticity in concrete?

Modulus of elasticity measures the stiffness of concrete, indicating how much it will deform under stress.

56. What is creep of concrete?

Creep is the long-term deformation of concrete under sustained load, leading to gradual deflection over time.

57. What is meant by durability of concrete?

Durability refers to concrete's ability to withstand weathering, chemical attack, abrasion, and other conditions without deteriorating.

58. What is the grade of concrete?

The grade of concrete is defined by its compressive strength, typically measured as MPa after 28 days of curing.

59. What are the functions of construction joints?

Construction joints allow for the interruption in concrete placement and provide a bonding surface for subsequent pours.

60. What is the purpose of curing compounds in concrete?

Curing compounds help retain moisture in concrete, aiding in the hydration process for strength development.

Explore essential Structural Engineer Interview Questions with expert answers, crafted for civil engineering professionals, job seekers, engineers, and students focused on structural design and analysis. This guide covers key Civil Engineering Questions related to steel reinforcement, RCC, concrete, frame structures, and superstructures. By addressing critical topics in structural stability, material properties, and design principles, candidates can prepare thoroughly for their interviews. Gaining proficiency in these fundamental areas is vital for aspiring structural engineers who aim to create safe and innovative structures in the ever-evolving field of civil engineering.