BE/B Eng Bachelor of Engineering Bachelor of Civil Engineering 3 — Questions and Answers
Question 1: In soil mechanics, the coefficient of consolidation (Cv) is used to predict:
- The shear strength of saturated clay
- The rate at which excess pore water pressure dissipates over time (Correct answer)
- The bearing capacity of a shallow foundation
- The angle of internal friction of granular soils
Correct answer: The rate at which excess pore water pressure dissipates over time
Cv governs the time-rate of consolidation settlement by describing how quickly pore water drains from compressible soil.
Question 2: Which mix design parameter primarily controls the strength of hardened concrete?
- Aggregate gradation
- Water-to-cement (w/c) ratio (Correct answer)
- Slump value
- Cement fineness
Correct answer: Water-to-cement (w/c) ratio
Abrams' law establishes that compressive strength is inversely related to the water-to-cement ratio for fully hydrated concrete.
Question 3: The Mohr-Coulomb failure criterion for soil defines shear strength as:
- τ = c + σ tan φ (Correct answer)
- τ = E × γ
- τ = c × N_c + q × N_q
- τ = σ_1 – σ_3
Correct answer: τ = c + σ tan φ
Shear strength equals cohesion (c) plus normal stress (σ) multiplied by the tangent of the internal friction angle (φ).
Question 4: In highway design, superelevation is applied to horizontal curves primarily to:
- Increase the sight distance around the curve
- Counteract the centrifugal force on vehicles negotiating the curve (Correct answer)
- Improve the aesthetic appearance of the roadway
- Reduce the pavement thickness requirement
Correct answer: Counteract the centrifugal force on vehicles negotiating the curve
Superelevation tilts the roadway cross-section inward so gravity assists in balancing centrifugal acceleration on the curve.
Question 5: According to ASTM D1143, the standard load test for deep foundations is the:
- Plate load test
- Cone penetration test (CPT)
- Static axial compressive load test on piles (Correct answer)
- Standard penetration test (SPT)
Correct answer: Static axial compressive load test on piles
ASTM D1143 specifies procedures for static axial compressive load testing to determine pile capacity and load-settlement behavior.
Question 6: What is the Manning's equation used for in hydraulics?
- Computing hydrostatic pressure at depth
- Estimating flow velocity in open channels (Correct answer)
- Determining pipe diameter for pressure flow
- Calculating sediment transport capacity
Correct answer: Estimating flow velocity in open channels
Manning's equation relates open-channel flow velocity to channel geometry, slope, and roughness coefficient (n).
Question 7: In prestressed concrete, post-tensioning differs from pre-tensioning in that:
- Post-tensioning uses lower-strength steel
- Tendons are stressed after the concrete has hardened (Correct answer)
- Pre-tensioning is done on-site while post-tensioning is done in the factory
- Post-tensioning does not use anchorage hardware
Correct answer: Tendons are stressed after the concrete has hardened
In post-tensioning, ducts are cast into the concrete and tendons are stressed and anchored after the concrete reaches sufficient strength.
BE/B Eng Bachelor of Engineering Bachelor of Civil Engineering 3
In soil mechanics, the coefficient of consolidation (Cv) is used to predict: