BE/B Eng Bachelor of Engineering Bachelor of Civil Engineering 5 — Questions and Answers
Question 1: In wastewater treatment, the Biochemical Oxygen Demand (BOD) test measures:
- The total dissolved solids in effluent
- The oxygen consumed by microorganisms decomposing organic matter over 5 days at 20°C (Correct answer)
- The chemical oxygen required to oxidize all organics
- The chlorine dose needed for disinfection
Correct answer: The oxygen consumed by microorganisms decomposing organic matter over 5 days at 20°C
BOD5 quantifies the amount of dissolved oxygen consumed by biological degradation of organic pollutants at 20°C over five days.
Question 2: The effective length factor (K) for a column with both ends pinned is:
- 0.5
- 0.7
- 1.0 (Correct answer)
- 2.0
Correct answer: 1.0
A pin-pin column buckles in a half-sine wave with an effective length equal to its actual length, giving K = 1.0.
Question 3: Which method is used to determine the California Bearing Ratio (CBR) of a subgrade soil?
- Triaxial compression test
- A penetration test comparing resistance to that of crushed limestone (Correct answer)
- Standard Proctor compaction test
- Plate load test at the ground surface
Correct answer: A penetration test comparing resistance to that of crushed limestone
CBR is determined by measuring the load required to penetrate a soil sample at specified rates compared to standard crushed limestone values.
Question 4: In open-channel hydraulics, critical flow occurs when the Froude number (Fr) equals:
- 0
- 0.5
- 1.0 (Correct answer)
- Greater than 1
Correct answer: 1.0
Critical flow is defined by Fr = V/√(gD) = 1, where inertial and gravitational forces are equal and specific energy is minimized for a given discharge.
Question 5: The primary advantage of using fiber-reinforced polymer (FRP) composites in civil structures is:
- Lower material cost compared to steel
- High strength-to-weight ratio and corrosion resistance (Correct answer)
- Easier welding and field modification
- Higher ductility and energy absorption than steel
Correct answer: High strength-to-weight ratio and corrosion resistance
FRP composites offer very high tensile strength at low weight and are immune to corrosion, making them ideal for harsh environments.
Question 6: In a two-way slab system, the Direct Design Method (ACI 318) can be applied only when:
- Slabs are supported by beams on all four sides and span ratio exceeds 2
- There are at least three continuous spans in each direction and the ratio of longer to shorter span ≤ 2 (Correct answer)
- The live load exceeds twice the dead load and columns are circular
- Slabs are post-tensioned and column capitals are present
Correct answer: There are at least three continuous spans in each direction and the ratio of longer to shorter span ≤ 2
ACI 318's Direct Design Method requires ≥3 spans each way, span aspect ratio ≤ 2, and live load ≤ 2× dead load among other conditions.
Question 7: Which type of contract delivery method gives the owner the highest degree of design control but typically the longest project schedule?
- Design-Build (DB)
- Construction Manager at Risk (CMaR)
- Design-Bid-Build (DBB) (Correct answer)
- Integrated Project Delivery (IPD)
Correct answer: Design-Bid-Build (DBB)
Design-Bid-Build is sequential — design must be fully complete before bidding and construction begin — giving owners full design control but the longest timeline.
BE/B Eng Bachelor of Engineering Bachelor of Civil Engineering 5
In wastewater treatment, the Biochemical Oxygen Demand (BOD) test measures: