BCE Bachelor of Civil Engineering 5 — Questions and Answers
Question 1: In prestressed concrete, post-tensioning differs from pre-tensioning in that:
- Post-tensioning uses higher strength steel
- Tendons are stressed after the concrete has hardened (Correct answer)
- Pre-tensioning requires more concrete cover
- Post-tensioning cannot be used in bridges
Correct answer: Tendons are stressed after the concrete has hardened
In post-tensioning, tendons are placed in ducts and stressed against the hardened concrete after it reaches sufficient strength.
Question 2: Which soil classification system is most widely used in geotechnical engineering practice in the United States?
- AASHTO Classification System
- Unified Soil Classification System (USCS) (Correct answer)
- FAO Soil Classification
- British Standard Classification
Correct answer: Unified Soil Classification System (USCS)
The Unified Soil Classification System (USCS) per ASTM D2487 is the standard system used in geotechnical engineering to classify soils by grain size and plasticity.
Question 3: The 'Bernoulli equation' in fluid mechanics assumes which of the following conditions?
- Compressible, viscous, unsteady flow
- Incompressible, inviscid, steady flow along a streamline (Correct answer)
- Turbulent flow with energy losses
- Non-uniform flow in a pipe bend
Correct answer: Incompressible, inviscid, steady flow along a streamline
Bernoulli's equation is derived under the assumptions of steady, incompressible, inviscid flow along a streamline.
Question 4: In structural steel design, the 'compact section' classification ensures that a beam can:
- Carry axial load without buckling
- Develop full plastic moment without local buckling (Correct answer)
- Resist fatigue at welded connections
- Support dynamic loads from earthquakes
Correct answer: Develop full plastic moment without local buckling
A compact section has sufficiently stocky flanges and web to allow the section to reach its plastic moment capacity (Mp) before local buckling occurs.
Question 5: Peak hour factor (PHF) in traffic engineering is used to:
- Calculate the average annual daily traffic
- Convert peak 15-minute flow rates to hourly volumes (Correct answer)
- Determine the design speed of a highway
- Estimate the pavement design life
Correct answer: Convert peak 15-minute flow rates to hourly volumes
PHF relates the highest 15-minute volume within the peak hour to the total hourly volume, accounting for traffic peaking within the hour.
Question 6: The critical path in a project schedule (CPM) is defined as the sequence of activities that:
- Has the most float or slack time
- Determines the minimum project completion time (Correct answer)
- Requires the highest cost resources
- Can be delayed without affecting the schedule
Correct answer: Determines the minimum project completion time
The critical path is the longest sequence of dependent activities, and any delay on it directly delays the project completion date.
Question 7: Which type of pile derives most of its load-carrying capacity from skin friction along its length rather than tip resistance?
- End-bearing pile
- Friction pile (Correct answer)
- Micropile
- Sheet pile
Correct answer: Friction pile
Friction piles transfer load to the surrounding soil primarily through interface shear (skin friction) along the pile shaft.
BCE Bachelor of Civil Engineering 5
In prestressed concrete, post-tensioning differs from pre-tensioning in that: