BE/B Eng Bachelor of Engineering Bachelor of Civil Engineering 4 — Questions and Answers
Question 1: Which type of retaining wall relies primarily on its own weight to resist overturning and sliding?
- Cantilever retaining wall
- Gravity retaining wall (Correct answer)
- Sheet pile wall
- Tieback wall
Correct answer: Gravity retaining wall
Gravity walls use the mass of the wall material (concrete, stone, or gabion) to resist earth pressure without significant bending action.
Question 2: In traffic engineering, Level of Service (LOS) 'F' on a signalized intersection means:
- Free-flow conditions with minimal delay
- Stable flow with acceptable delay under 35 seconds
- Near-capacity operation with long queues
- Breakdown flow with demand exceeding capacity (Correct answer)
Correct answer: Breakdown flow with demand exceeding capacity
LOS F represents forced or breakdown flow where arrival demand exceeds intersection capacity, causing overflow queues and unacceptable delay.
Question 3: The Dupuit assumption in groundwater flow analysis states that:
- Flow in aquifers is always vertical
- Flow lines are horizontal and hydraulic gradient equals the slope of the water table (Correct answer)
- Permeability is isotropic in all directions
- Groundwater pressure is equal to atmospheric pressure
Correct answer: Flow lines are horizontal and hydraulic gradient equals the slope of the water table
Dupuit's assumption simplifies unconfined aquifer analysis by assuming equipotential lines are vertical and flow is essentially horizontal.
Question 4: Which welding defect is most commonly detected using radiographic (X-ray) testing?
- Surface cracks
- Internal porosity and inclusions (Correct answer)
- Undercut at the weld toe
- Distortion of the base metal
Correct answer: Internal porosity and inclusions
Radiographic testing excels at detecting internal volumetric defects such as porosity, slag inclusions, and incomplete fusion within the weld.
Question 5: The Darcy-Weisbach equation in pipe flow relates head loss to:
- Flow velocity, pipe diameter, friction factor, and pipe length (Correct answer)
- Reynolds number, kinematic viscosity, and pipe roughness only
- Pipe material, fluid density, and pipe slope
- Flow rate, pipe area, and discharge coefficient
Correct answer: Flow velocity, pipe diameter, friction factor, and pipe length
Darcy-Weisbach: h_f = f(L/D)(V²/2g), linking friction head loss to the friction factor, pipe length-to-diameter ratio, and velocity head.
Question 6: In structural steel design (AISC LRFD), the design strength is expressed as:
- Rn / Ω ≥ Ra
- φRn ≥ Ru (Correct answer)
- Rn × SF ≥ Ra
- Ru / φ ≥ Rn
Correct answer: φRn ≥ Ru
LRFD requires that the factored resistance (φRn) equals or exceeds the factored load demand (Ru), where φ is the resistance factor.
Question 7: A proctor compaction test determines the relationship between soil moisture content and:
- Shear strength
- Permeability
- Dry unit weight (Correct answer)
- Plasticity index
Correct answer: Dry unit weight
The Proctor test plots dry unit weight versus moisture content to find the optimum moisture content for maximum dry density.
BE/B Eng Bachelor of Engineering Bachelor of Civil Engineering 4
Which type of retaining wall relies primarily on its own weight to resist overturning and sliding?